seven-transmembrane G protein-coupled receptor superfamily; This hierarchical evolutionary model represents the seven-transmembrane (7TM) receptors, often referred to as G protein-coupled receptors (GPCRs), which transmit physiological signals from the outside of the cell to the inside via G proteins. GPCRs constitute the largest known superfamily of transmembrane receptors across the three kingdoms of life that respond to a wide variety of extracellular stimuli including peptides, lipids, neurotransmitters, amino acids, hormones, and sensory stimuli such as light, smell and taste. All GPCRs share a common structural architecture comprising of seven-transmembrane (TM) alpha-helices interconnected by three extracellular and three intracellular loops. A general feature of GPCR signaling is agonist-induced conformational changes in the receptors, leading to activation of the heterotrimeric G proteins, which consist of the guanine nucleotide-binding G-alpha subunit and the dimeric G-beta-gamma subunits. The activated G proteins then bind to and activate numerous downstream effector proteins, which generate second messengers that mediate a broad range of cellular and physiological processes. However, some 7TM receptors, such as the type 1 microbial rhodopsins, do not activate G proteins. Based on sequence similarity, GPCRs can be divided into six major classes: class A (the rhodopsin-like family), class B (the Methuselah-like, adhesion and secretin-like receptor family), class C (the metabotropic glutamate receptor family), class D (the fungal mating pheromone receptors), class E (the cAMP receptor family), and class F (the frizzled/smoothened receptor family). Nearly 800 human GPCR genes have been identified and are involved essentially in all major physiological processes. Approximately 40% of clinically marketed drugs mediate their effects through modulation of GPCR function for the treatment of a variety of human diseases including bacterial infections.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*
gi 45647651 228 EAKRERKAAQTLAIITGAFVICWLPFFVMALTMSLCKECEIHTAVASLFLWLGYFNSTLNPVIYTIFNPEFRRAF 302
Cdd:cd15064 184 AAARERKAAKTLGIILGAFIVCWLPFFLVALIVPLCSHCWIPLALKSFFLWLGYFNSLINPLIYTFFNKDFRKAF 258

serotonin receptor subtypes 1, 5 and 7, member of the class A family of seven-transmembrane G protein-coupled receptors; This group includes serotonin receptor subtypes 1, 5, and 7 that are activated by the neurotransmitter serotonin. The 5-HT1 and 5-HT5 receptors mediate inhibitory neurotransmission by coupling to G proteins of the G(i/o) family. The 5-HT1 receptor subfamily includes 5-HT1A, 5-HT1B, 5-HT1D, 5-HT1E, and 5-HT1F. There is no 5-HT1C receptor subtype, as it has been reclassified as 5-HT2C receptor. The 5-HT5A and 5-HT5B receptors have been cloned from rat and mouse, but only the 5-HT5A isoform has been identified in human because of the presence of premature stop codons in the human 5-HT5B gene, which prevents a functional receptor from being expressed. The 5-HT7 receptor is coupled to Gs, which positively stimulates adenylate cyclase activity, leading to increased intracellular cAMP formation and calcium influx. In the CNS, serotonin is involved in the regulation of appetite, mood, sleep, cognition, learning and memory, as well as implicated in neurologic disorders such as migraine, schizophrenia, and depression.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*
gi 45647651 228 EAKRERKAAQTLAIITGAFVICWLPFFVMALTMSLCKECEIHTAVASLFLWLGYFNSTLNPVIYTIFNPEFRRAF 302
Cdd:cd15064 184 AAARERKAAKTLGIILGAFIVCWLPFFLVALIVPLCSHCWIPLALKSFFLWLGYFNSLINPLIYTFFNKDFRKAF 258

serotonin receptor subtypes 1, 5 and 7, member of the class A family of seven-transmembrane G protein-coupled receptors; This group includes serotonin receptor subtypes 1, 5, and 7 that are activated by the neurotransmitter serotonin. The 5-HT1 and 5-HT5 receptors mediate inhibitory neurotransmission by coupling to G proteins of the G(i/o) family. The 5-HT1 receptor subfamily includes 5-HT1A, 5-HT1B, 5-HT1D, 5-HT1E, and 5-HT1F. There is no 5-HT1C receptor subtype, as it has been reclassified as 5-HT2C receptor. The 5-HT5A and 5-HT5B receptors have been cloned from rat and mouse, but only the 5-HT5A isoform has been identified in human because of the presence of premature stop codons in the human 5-HT5B gene, which prevents a functional receptor from being expressed. The 5-HT7 receptor is coupled to Gs, which positively stimulates adenylate cyclase activity, leading to increased intracellular cAMP formation and calcium influx. In the CNS, serotonin is involved in the regulation of appetite, mood, sleep, cognition, learning and memory, as well as implicated in neurologic disorders such as migraine, schizophrenia, and depression.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*
gi 45647651 228 EAKRERKAAQTLAIITGAFVICWLPFFVMALTMSLCKECEIHTAVASLFLWLGYFNSTLNPVIYTIFNPEFRRAF 302
Cdd:cd15064 184 AAARERKAAKTLGIILGAFIVCWLPFFLVALIVPLCSHCWIPLALKSFFLWLGYFNSLINPLIYTFFNKDFRKAF 258

amine receptors and similar proteins, member of the class A family of seven-transmembrane G protein-coupled receptors; Amine receptors of the class A family of GPCRs include adrenoceptors, 5-HT (serotonin) receptors, muscarinic cholinergic receptors, dopamine receptors, histamine receptors, and trace amine receptors. The receptors of amine subfamily are major therapeutic targets for the treatment of neurological disorders and psychiatric diseases. All GPCRs have a common structural architecture comprising of seven-transmembrane (TM) alpha-helices interconnected by three extracellular and three intracellular loops. A general feature of GPCR signaling is agonist-induced conformational changes in the receptors, leading to activation of the heterotrimeric G proteins, which consist of the guanine nucleotide-binding G-alpha subunit and the dimeric G-beta-gamma subunits. The activated G proteins then bind to and activate numerous downstream effector proteins, which generate second messengers that mediate a broad range of cellular and physiological processes.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....
gi 45647651 229 AKRERKAAQTLAIITGAFVICWLPFFVMALTMSLCKECEIHTAVASLFLWLGYFNSTLNPVIYTIFNPEFRRAF 302
Cdd:cd14967 186 ARRELKAAKTLAIIVGAFLLCWLPFFIIYLVSAFCPPDCVPPILYAVFFWLGYLNSALNPIIYALFNRDFRRAF 259

serotonin receptor subtype 7, member of the class A family of seven-transmembrane G protein-coupled receptors; The 5-HT7 receptor, one of 14 mammalian serotonin receptors, is a member of the class A of GPCRs and is activated by the neurotransmitter serotonin (5-hydroxytryptamine, 5-HT). 5-HT7 receptor mainly couples to Gs protein, which positively stimulates adenylate cyclase, leading to increased intracellular cAMP formation and calcium influx. 5-HT7 receptor is expressed in various human tissues, mainly in the brain, the lower gastrointestinal tract and in vital blood vessels including the coronary artery. In the CNS, serotonin is involved in the regulation of appetite, mood, sleep, cognition, learning and memory, as well as implicated in neurologic disorders such as migraine, schizophrenia, and depression.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 45647651 227 LEAKRERKAAQTLAIITGAFVICWLPFFVMALTMSLCK---ECEIHTAVASLFLWLGYFNSTLNPVIYTIFNPEFRRAF 302
Cdd:cd15329 182 RAAKSERKAIKTLGIIMGAFTLCWLPFFILALLRPFLKpikCSCIPLWLSRLFLWLGYANSFLNPIIYAKFNREFRTPF 260

Drosophila melanogaster beta-adrenergic receptor-like octopamine receptors and similar receptors in bilateria; member of the class A family of seven-transmembrane G protein-coupled receptors; This group includes Drosophila beta-adrenergic-like octopamine receptors and similar proteins. The biogenic amine octopamine is the invertebrate equivalent of vertebrate adrenergic neurotransmitters and exerts its effects through different G protein-coupled receptor types. Insect octopamine receptors are involved in the modulation of carbohydrate metabolism, muscular tension, cognition and memory. The activation of octopamine receptors mediating these actions leads to an increase in adenylate cyclase activity, thereby increasing cAMP levels. In Drosophila melanogaster, three subgroups have been classified on the basis of their structural homology and functional equivalents with vertebrate beta-adrenergic receptors: DmOctBeta1R, DmOctBeta2R, and DmOctBeta3R.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 45647651 224 RQLLEAKRERKAAQTLAIITGAFVICWLPFFVMALTMSLCK-ECEIHTAVASLFLWLGYFNSTLNPVIYTIFNPEFRRAF 302
Cdd:cd15066 186 RIYLEAKREHKAAKTLGIIMGAFILCWLPFFLWYVTTTLCGdACPYPPILVSILFWIGYFNSTLNPLIYAYFNRDFREAF 265

serotonin receptor subtype 2, member of the class A family of seven-transmembrane G protein-coupled receptors; The 5-HT2 receptors are a subfamily of serotonin receptors that bind the neurotransmitter serotonin (5HT; 5-hydroxytryptamine) in the central nervous system (CNS). The 5-HT2 subfamily is composed of three subtypes that mediate excitatory neurotransmission: 5-HT2A, 5-HT2B, and 5-HT2C. They are selectively linked to G proteins of the G(q/11) family and activate phospholipase C, which leads to activation of protein kinase C and calcium release. In the CNS, serotonin is involved in the regulation of appetite, mood, sleep, cognition, learning and memory, as well as implicated in diseases such as migraine, schizophrenia, and depression. Indeed, 5-HT2 receptors are attractive targets for a variety of psychoactive drugs, ranging from atypical antipsychotic drugs, antidepressants, and anxiolytics, which have an antagonistic action on 5-HT2 receptors, to hallucinogens, which act as agonists at postsynaptic 5-HT2 receptors. All GPCRs have a common structural architecture comprising of seven-transmembrane (TM) alpha-helices interconnected by three extracellular and three intracellular loops. A general feature of GPCR signaling is agonist-induced conformational changes in the receptors, leading to activation of the heterotrimeric G proteins, which consist of the guanine nucleotide-binding G-alpha subunit and the dimeric G-beta-gamma subunits. The activated G proteins then bind to and activate numerous downstream effector proteins, which generate second messengers that mediate a broad range of cellular and physiological processes.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....
gi 45647651 231 RERKAAQTLAIITGAFVICWLPFFVMALTMSLCKECE--IHTAVASLFLWLGYFNSTLNPVIYTIFNPEFRRAF 302
Cdd:cd15052 189 NEQKASKVLGIVFAVFVICWCPFFITNILTGLCEECNcrISPWLLSVFVWLGYVSSTINPIIYTIFNKTFRRAF 262

serotonin receptor subtypes B1 and B2 from Aplysia californica and similar proteins; member of the class A family of seven-transmembrane G protein-coupled receptors; This subfamily includes Aplysia californica serotonin receptors Ap5-HTB1 and Ap5-HTB2, and similar proteins from bilateria including insects, mollusks, annelids, and worms. Ap5-HTB1 is one of the several different receptors for 5-hydroxytryptamine (5HT, serotonin). In Aplysia, serotonin plays important roles in a variety of behavioral and physiological processes mediated by the central nervous system. These include circadian clock, feeding, locomotor movement, cognition and memory, synaptic growth and synaptic plasticity. Both Ap5-HTB1 and Ap5-HTB2 receptors are coupled to G-proteins that stimulate phospholipase C, leading to the activation of phosphoinositide metabolism. Ap5-HTB1 is expressed in the reproductive system, whereas Ap5-HTB2 is expressed in the central nervous system.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|..
gi 45647651 231 RERKAAQTLAIITGAFVICWLPFFVMALTMSLCKECeIHTAVASLFLWLGYFNSTLNPVIYTIFNPEFRRAF 302
Cdd:cd15065 230 SDHKAAVTLGIIMGVFLICWLPFFIINIIAAFCKTC-IPPKCFKILTWLGYFNSCLNPIIYSIFNSEFRRAF 300

D3 subtype of the D2-like family of dopamine receptors, member of the class A family of seven-transmembrane G protein-coupled receptors; Dopamine receptors are members of the class A G protein-coupled receptors that are involved in many neurological processes in the central nervous system (CNS). The neurotransmitter dopamine is the primary endogenous agonist for dopamine receptors. Dopamine receptors consist of at least five subtypes: D1, D2, D3, D4, and D5. The D1 and D5 subtypes are members of the D1-like family of dopamine receptors, whereas the D2, D3 and D4 subtypes are members of the D2-like family. Activation of D2-like family receptors is linked to G proteins of the G(i) family. This leads to a decrease in adenylate cyclase activity, thereby decreasing cAMP levels. Dopamine receptors are major therapeutic targets for neurological and psychiatric disorders such as drug abuse, depression, schizophrenia, or Parkinson's disease.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|..
gi 45647651 231 RERKAAQTLAIITGAFVICWLPFFVMALTMSLCKECEIHTAVASLFLWLGYFNSTLNPVIYTIFNPEFRRAF 302
Cdd:cd15310 188 REKKATQMLAIVLGAFIVCWLPFFLTHILNTHCQACHVPPELYSATTWLGYVNSALNPVIYTTFNIEFRRAF 259

trace amine-associated receptors, member of the class A family of seven-transmembrane G protein-coupled receptors; The trace amine-associated receptors (TAARs) are a distinct subfamily within the class A G protein-coupled receptor family. Trace amines are endogenous amines of unknown function that have strong structural and metabolic similarity to classical monoamine neurotransmitters (serotonin, noradrenaline, adrenaline, dopamine, and histamine), which play critical roles in human and animal physiological activities such as cognition, consciousness, mood, motivation, perception, and autonomic responses. However, trace amines are found in the mammalian brain at very low concentrations compared to classical monoamines. Trace amines, including p-tyramine, beta-phenylethylamine, and tryptamine, are also thought to act as chemical messengers to exert their biological effects in vertebrates. All GPCRs have a common structural architecture comprising of seven-transmembrane (TM) alpha-helices interconnected by three extracellular and three intracellular loops. A general feature of GPCR signaling is agonist-induced conformational changes in the receptors, leading to activation of the heterotrimeric G proteins, which consist of the guanine nucleotide-binding G-alpha subunit and the dimeric G-beta-gamma subunits. The activated G proteins then bind to and activate numerous downstream effector proteins, which generate second messengers that mediate a broad range of cellular and physiological processes.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|...
gi 45647651 230 KRERKAAQTLAIITGAFVICWLPFFVMALTMSLCKeceIHTAVASLFLWLGYFNSTLNPVIYTIFNPEFRRAF 302
Cdd:cd15055 216 KSERKAAKTLGIVVGVFLLCWLPYYIVSLVDPYIS---TPSSVFDVLIWLGYFNSCLNPLIYALFYPWFRKAL 285

histamine subtype H2 receptor, member of the class A family of seven-transmembrane G protein-coupled receptors; This group includes histamine receptor subtype H2R, a member of histamine receptor family, which belongs to the class A of GPCRs. Histamine plays a key role as chemical mediator and neurotransmitter in various physiological and pathophysiological processes in the central and peripheral nervous system. Histamine exerts its functions by binding to four different G protein-coupled receptors (H1-H4). The H2R subtype selectively interacts with the G(s)-type G protein that activates adenylate cyclase, leading to increased cAMP production and activation of Protein Kinase A. H2R is found in various tissues such as the brain, stomach, and heart. Its most prominent role is in histamine-induced gastric acid secretion. All GPCRs have a common structural architecture comprising of seven-transmembrane (TM) alpha-helices interconnected by three extracellular and three intracellular loops. A general feature of GPCR signaling is agonist-induced conformational changes in the receptors, leading to activation of the heterotrimeric G proteins, which consist of the guanine nucleotide-binding G-alpha subunit and the dimeric G-beta-gamma subunits. The activated G proteins then bind to and activate numerous downstream effector proteins, which generate second messengers that mediate a broad range of cellular and physiological processes.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 45647651 221 AKRRQLLEAKRERKAAQTLAIITGAFVICWLPFFVMALTMSLCKeCEIHTAVASLFLWLGYFNSTLNPVIYTIFNPEFRR 300
Cdd:cd15051 207 ANSSKSAATAREHKATVTLAAVLGAFIICWFPYFTYFTYRGLCG-DNINETALSVVLWLGYANSALNPILYAFLNRDFRR 285

                ..
gi 45647651 301 AF 302
Cdd:cd15051 286 AF 287

octopamine receptors in invertebrates, member of the class A family of seven-transmembrane G protein-coupled receptors; G-protein coupled receptor for octopamine (OA), which functions as a neurotransmitter, neurohormone, and neuromodulator in invertebrate nervous system. Octopamine (also known as beta, 4-dihydroxyphenethylamine) is an endogenous trace amine that is highly similar to norepinephrine, but lacks a hydroxyl group, and has effects on the adrenergic and dopaminergic nervous systems. Based on the pharmacological and signaling profiles, the octopamine receptors can be classified into at least two groups: OA1 receptors elevate intracellular calcium levels in muscle, whereas OA2 receptors activate adenylate cyclase and increase cAMP production.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....
gi 45647651 229 AKRERKAAQTLAIITGAFVICWLPFFVMALTMSLCKECeIHTAVASLFLWLGYFNSTLNPVIYTIFNPEFRRAF 302
Cdd:cd15063 194 ARMETKAAKTVAIIVGCFIFCWLPFFTVYLVRAFCEDC-IPPLLFSVFFWLGYCNSALNPCIYALFSRDFRFAF 266

D1-like family of dopamine receptors, member of the class A family of seven-transmembrane G protein-coupled receptors; Dopamine receptors are members of the class A G protein-coupled receptors that are involved in many neurological processes in the central nervous system (CNS). The neurotransmitter dopamine is the primary endogenous agonist for dopamine receptors. Dopamine receptors consist of at least five subtypes: D1, D2, D3, D4, and D5. The D1 and D5 subtypes are members of the D1-like family of dopamine receptors, whereas the D2, D3 and D4 subtypes are members of the D2-like family. The D1-like family receptors are coupled to G proteins of the G(s) family, which activate adenylate cyclase, causing cAMP formation and activation of protein kinase A. In contrast, activation of D2-like family receptors is linked to G proteins of the G(i) family, which inhibit adenylate cyclase. Dopamine receptors are major therapeutic targets for neurological and psychiatric disorders such as drug abuse, depression, schizophrenia, or Parkinson's disease. All GPCRs have a common structural architecture comprising of seven-transmembrane (TM) alpha-helices interconnected by three extracellular and three intracellular loops. A general feature of GPCR signaling is agonist-induced conformational changes in the receptors, leading to activation of the heterotrimeric G proteins, which consist of the guanine nucleotide-binding G-alpha subunit and the dimeric G-beta-gamma subunits. The activated G proteins then bind to and activate numerous downstream effector proteins, which generate second messengers that mediate a broad range of cellular and physiological processes.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 45647651 230 KRERKAAQTLAIITGAFVICWLPFFVMALTMSLC------KECEIHTaVASLFLWLGYFNSTLNPVIYTiFNPEFRRAF 302
Cdd:cd15057 223 RRETKALKTLSIIMGVFVCCWLPFFILNCVLPFCdlrtaqFPCVPDT-TFIVFVWLGWANSSLNPIIYA-FNADFRKAF 299

alpha-1 adrenergic receptors, member of the class A family of seven-transmembrane G protein-coupled receptors; The alpha-1 adrenergic receptors (or adrenoceptors) are a subfamily of the class A rhodopsin-like GPCRs that share a common architecture of seven transmembrane helices. This subfamily consists of three highly homologous receptor subtypes that primarily mediate smooth muscle contraction: alpha-1A, alpha-1B, and alpha-1D. Activation of alpha-1 receptors by catecholamines such as norepinephrine and epinephrine couples to the G(q) protein, which then activates the phospholipase C pathway, leading to an increase in IP3 and calcium. Consequently, the elevation of intracellular calcium concentration leads to vasoconstriction in smooth muscle of blood vessels. In addition, activation of alpha-1 receptors by phenylpropanolamine (PPA) produces anorexia and may induce appetite suppression in rats.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 45647651 227 LEAKRERKAAQTLAIITGAFVICWLPFFVMALTMSLCKECEIHTAVASLFLWLGYFNSTLNPVIYTIFNPEFRRAF 302
Cdd:cd15062 186 FKFSREKKAAKTLGIVVGAFVLCWFPFFVVLPLGSLFSTLKPPEPVFKVVFWLGYFNSCLNPIIYPCSSREFKRAF 261

muscarinic acetylcholine receptor subfamily, member of the class A family of seven-transmembrane G protein-coupled receptors; Muscarinic acetylcholine receptors (mAChRs) regulate the activity of many fundamental central and peripheral functions. The mAChR family consists of 5 subtypes M1-M5, which can be further divided into two major groups according to their G-protein coupling preference. The M1, M3 and M5 receptors selectively interact with G proteins of the G(q/11) family, whereas the M2 and M4 receptors preferentially link to the G(i/o) types of G proteins. Activation of mAChRs by agonist (acetylcholine) leads to a variety of biochemical and electrophysiological responses. In general, the exact nature of these responses and the subsequent physiological effects mainly depend on the molecular and pharmacological identity of the activated receptor subtype(s). All GPCRs have a common structural architecture comprising of seven-transmembrane (TM) alpha-helices interconnected by three extracellular and three intracellular loops. A general feature of GPCR signaling is agonist-induced conformational changes in the receptors, leading to activation of the heterotrimeric G proteins, which consist of the guanine nucleotide-binding G-alpha subunit and the dimeric G-beta-gamma subunits. The activated G proteins then bind to and activate numerous downstream effector proteins, which generate second messengers that mediate a broad range of cellular and physiological processes.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 45647651 227 LEAKRERKAAQTLAIITGAFVICWLPFFVMALTMSLCKECeIHTAVASLFLWLGYFNSTLNPVIYTIFNPEFRRAF 302
Cdd:cd15049 188 RETARERKAARTLSAILLAFIITWTPYNILVLVSTFCAKC-IPDTLWSFGYWLCYINSTINPFCYALCNKTFRKTF 262

alpha-2 adrenergic receptors subtype B, member of the class A family of seven-transmembrane G protein-coupled receptors; The alpha-2 adrenergic receptors (or adrenoceptors) are a subfamily of the class A rhodopsin-like GPCRs that share a common architecture of seven transmembrane helices. This subfamily consists of three highly homologous receptor subtypes that have a key role in neurotransmitter release: alpha-2A, alpha-2B, and alpha-2C. In addition, a fourth subtype, alpha-2D is present in ray-finned fishes and amphibians, but is not found in humans. The alpha-2 receptors are found in both central and peripheral nervous system and serve to produce inhibitory functions through the G(i) proteins. Thus, the alpha-2 receptors inhibit adenylate cyclase, which decreases cAMP production and thereby decreases calcium influx during the action potential. Consequently, lowered levels of calcium will lead to a decrease in neurotransmitter release by negative feedback.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 45647651 223 RRQLLEAKRERKAAQTLAIITGAFVICWLPFFVMALTMSLCKE-CEIHTAVASLFLWLGYFNSTLNPVIYTIFNPEFRRA 301
Cdd:cd15321 188 RIYLIAKNREKRFTFVLAVVIGVFVLCWFPFFFSYSLGAICPElCKVPHSLFQFFFWIGYCNSSLNPVIYTIFNQDFRRA 267

                .
gi 45647651 302 F 302
Cdd:cd15321 268 F 268

alpha-2 adrenergic receptors subtype D, member of the class A family of seven-transmembrane G protein-coupled receptors; The alpha-2 adrenergic receptors (or adrenoceptors) are a subfamily of the class A rhodopsin-like GPCRs that share a common architecture of seven transmembrane helices. This subfamily consists of three highly homologous receptor subtypes that have a key role in neurotransmitter release: alpha-2A, alpha-2B, and alpha-2C. In addition, a fourth subtype, alpha-2D is present in ray-finned fishes and amphibians, but is not found in humans. The alpha-2 receptors are found in both central and peripheral nervous system and serve to produce inhibitory functions through the G(i) proteins. Thus, the alpha-2 receptors inhibit adenylate cyclase, which decreases cAMP production and thereby decreases calcium influx during the action potential. Consequently, lowered levels of calcium will lead to a decrease in neurotransmitter release by negative feedback.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|...
gi 45647651 231 RERKAAQTLAIITGAFVICWLPFFVMALTMSLCKE-CEIHTAVASLFLWLGYFNSTLNPVIYTIFNPEFRRAF 302
Cdd:cd15324 184 REKRFTFVLAVVMGVFVLCWFPFFFTYSLHAVCRKrCGIPDALFNLFFWIGYCNSSVNPIIYTIFNRDFRKAF 256

serotonin receptor subtype 5, member of the class A family of seven-transmembrane G protein-coupled receptors; 5-HT5 receptor, one of 14 mammalian 5-HT receptors, is activated by the neurotransmitter and peripheral signal mediator serotonin (also known as 5-hydroxytryptamine or 5-HT). The 5-HT5A and 5-HT5B receptors have been cloned from rat and mouse, but only the 5-HT5A isoform has been identified in human because of the presence of premature stop codons in the human 5-HT5B gene, which prevents a functional receptor from being expressed. 5-HT5 receptors mediate inhibitory neurotransmission by coupling to G proteins of the G(i/0) family, which lead to a decrease in adenylate cyclase activity, thereby decreasing intracellular cAMP levels and calcium influx. In the CNS, serotonin is involved in the regulation of appetite, mood, sleep, cognition, learning and memory, as well as implicated in neurologic disorders such as migraine, schizophrenia, and depression.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....
gi 45647651 229 AKRERKAAQTLAIITGAFVICWLPFFVMALTMSLCkECEIHTAVASLFLWLGYFNSTLNPVIYTIFNPEFRRAF 302
Cdd:cd15328 187 AQKEKRAALMVGILIGVFVLCWIPFFLTELISPLC-SCDIPPIWKSIFLWLGYSNSFFNPLIYTAFNKNYNNAF 259

serotonin receptor subtype 4, member of the class A family of seven-transmembrane G protein-coupled receptors; The 5-HT4 subtype is a member of the serotonin receptor family that belongs to the class A G protein-coupled receptors, and binds the neurotransmitter serotonin (5HT; 5-hydroxytryptamine) in the mammalian central nervous system (CNS). 5-HT4 receptors are selectively linked to G proteins of the G(s) family, which positively stimulate adenylate cyclase, causing cAMP formation and activation of protein kinase A. 5-HT4 receptor-specific agonists have been shown to enhance learning and memory in animal studies. Moreover, hippocampal 5-HT4 receptor expression has been reported to be inversely correlated with memory performance in humans. All GPCRs have a common structural architecture comprising of seven-transmembrane (TM) alpha-helices interconnected by three extracellular and three intracellular loops. A general feature of GPCR signaling is agonist-induced conformational changes in the receptors, leading to activation of the heterotrimeric G proteins, which consist of the guanine nucleotide-binding G-alpha subunit and the dimeric G-beta-gamma subunits. The activated G proteins then bind to and activate numerous downstream effector proteins, which generate second messengers that mediate a broad range of cellular and physiological processes.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|...
gi 45647651 230 KRERKAAQTLAIITGAFVICWLPFFVMALTMSLCKEcEIHTAVASLFLWLGYFNSTLNPVIYTIFNPEFRRAF 302
Cdd:cd15056 223 RTETKAAKTLGIIMGCFCVCWAPFFVTNIVDPFIGY-RVPYLLWTAFLWLGYINSGLNPFLYAFFNKSFRRAF 294

serotonin receptor subtype 1E, member of the class A family of seven-transmembrane G protein-coupled receptors; The 5-HT1 receptors, one of 14 mammalian 5-HT receptors, is a member of the class A of GPCRs and is activated by the endogenous neurotransmitter and peripheral signal mediator serotonin (5-hydroxytryptamine, 5-HT). The 5-HT1 receptors mediate inhibitory neurotransmission by coupling to G proteins of the G(i/o) family, which lead to a decrease in adenylate cyclase activity, thereby decreasing intracellular cAMP levels and calcium influx. The 5-HT1 receptor subfamily includes 5 subtypes: 5-HT1A, 5-HT1B, 5-HT1D, 5-HT1E, and 5-HT1F. There is no 5-HT1C receptor subtype, as it has been reclassified as the 5-HT2C receptor. In the CNS, serotonin is involved in the regulation of appetite, mood, sleep, cognition, learning and memory, as well as implicated in neurologic disorders such as migraine, schizophrenia, and depression.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....
gi 45647651 229 AKRERKAAQTLAIITGAFVICWLPFFVMALTMSLcKECEIHTAVASLFLWLGYFNSTLNPVIYTIFNPEFRRAF 302
Cdd:cd15335 186 ASRERKAARILGLILGAFILSWLPFFIKELIVGL-SVMTVSPEVADFLTWLGYVNSLVNPLLYTSFNEDFKLAF 258

serotonin receptor subtype 6, member of the class A family of seven-transmembrane G protein-coupled receptors; The 5-HT6 receptors are a subfamily of serotonin receptors that bind the neurotransmitter serotonin (5HT; 5-hydroxytryptamine) in the mammalian central nervous system (CNS). 5-HT6 receptors are selectively linked to G proteins of the G(s) family, which positively stimulate adenylate cyclase, causing cAMP formation and activation of protein kinase A. The 5-HT6 receptors mediates excitatory neurotransmission and are involved in learning and memory; thus they are promising targets for the treatment of cognitive impairment. All GPCRs have a common structural architecture comprising of seven-transmembrane (TM) alpha-helices interconnected by three extracellular and three intracellular loops. A general feature of GPCR signaling is agonist-induced conformational changes in the receptors, leading to activation of the heterotrimeric G proteins, which consist of the guanine nucleotide-binding G-alpha subunit and the dimeric G-beta-gamma subunits. The activated G proteins then bind to and activate numerous downstream effector proteins, which generate second messengers that mediate a broad range of cellular and physiological processes.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 45647651 224 RQLLEAKRERKAAQTLAIITGAFVICWLPFFVMALTMSLCkECeIHTAVASLFLWLGYFNSTLNPVIYTIFNPEFRRAF 302
Cdd:cd15054 191 RILLAARKALKASLTLGILLGMFFVTWLPFFVANVVQAVC-DC-VSPGLFDVLTWLGYCNSTMNPIIYPLFMRDFKRAL 267

alpha-1 adrenergic receptors subtype B, member of the class A family of seven-transmembrane G protein-coupled receptors; The alpha-1 adrenergic receptors (or adrenoceptors) are a subfamily of the class A rhodopsin-like GPCRs that share a common architecture of seven transmembrane helices. This subfamily consists of three highly homologous receptor subtypes that primarily mediate smooth muscle contraction: alpha-1A, alpha-1B, and alpha-1D. Activation of alpha-1 receptors by catecholamines such as norepinephrine and epinephrine couples to the G(q) protein, which then activates the phospholipase C pathway, leading to an increase in IP3 and calcium. Consequently, the elevation of intracellular calcium concentration leads to vasoconstriction in smooth muscle of blood vessels. In addition, activation of alpha-1 receptors by phenylpropanolamine (PPA) produces anorexia and may induce appetite suppression in rats.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 45647651 227 LEAKRERKAAQTLAIITGAFVICWLPFFVMALTMSLCKECEIHTAVASLFLWLGYFNSTLNPVIYTIFNPEFRRAF 302
Cdd:cd15326 186 LKFSREKKAAKTLGIVVGMFILCWLPFFIALPLGSLFSHLKPPETLFKIIFWLGYFNSCLNPIIYPCSSKEFKRAF 261

trace amine-associated receptor 5 and similar receptors, member of the class A family of seven-transmembrane G protein-coupled receptors; Included in this group are mammalian TAAR5, TAAR6, TAAR8, TAAR9, and similar proteins. They are among the 15 identified trace amine-associated receptors (TAARs), a distinct subfamily within the class A G protein-coupled receptors. Trace amines are endogenous amines of unknown function that have strong structural and metabolic similarity to classical monoamine neurotransmitters (serotonin, noradrenaline, adrenaline, dopamine, and histamine), which play critical roles in human and animal physiological activities such as cognition, consciousness, mood, motivation, perception, and autonomic responses. However, trace amines are found in the mammalian brain at very low concentrations compared to classical monoamines. Trace amines, including p-tyramine, beta-phenylethylamine, and tryptamine, are also thought to act as chemical messengers to exert their biological effects in vertebrates. All GPCRs have a common structural architecture comprising of seven-transmembrane (TM) alpha-helices interconnected by three extracellular and three intracellular loops. A general feature of GPCR signaling is agonist-induced conformational changes in the receptors, leading to activation of the heterotrimeric G proteins, which consist of the guanine nucleotide-binding G-alpha subunit and the dimeric G-beta-gamma subunits. The activated G proteins then bind to and activate numerous downstream effector proteins, which generate second messengers that mediate a broad range of cellular and physiological processes.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....
gi 45647651 229 AKRERKAAQTLAIITGAFVICWLPFFVMALTMSLCkECEIHTAVASLFLWLGYFNSTLNPVIYTIFNPEFRRAF 302
Cdd:cd15317 218 ASRERKAAKTLAIVMGIFLFCWLPYFIDTIVDEYS-NFITPAIVFDAVIWLGYFNSAFNPFIYAFFYPWFRKAF 290

histamine receptor subtypes H3R and H4R, member of the class A family of seven-transmembrane G protein-coupled receptors; This group includes histamine subtypes H3R and H4R, members of the histamine receptor family, which belong to the class A of GPCRs. Histamine plays a key role as chemical mediator and neurotransmitter in various physiological and pathophysiological processes in the central and peripheral nervous system. Histamine exerts its functions by binding to four different G protein-coupled receptors (H1-H4). The H3 and H4 receptors couple to the G(i)-proteins, which leading to the inhibition of cAMP formation. The H3R receptor functions as a presynaptic autoreceptors controlling histamine release and synthesis. The H4R plays an important role in histamine-mediated chemotaxis in mast cells and eosinophils. All GPCRs have a common structural architecture comprising of seven-transmembrane (TM) alpha-helices interconnected by three extracellular and three intracellular loops. A general feature of GPCR signaling is agonist-induced conformational changes in the receptors, leading to activation of the heterotrimeric G proteins, which consist of the guanine nucleotide-binding G-alpha subunit and the dimeric G-beta-gamma subunits. The activated G proteins then bind to and activate numerous downstream effector proteins, which generate second messengers that mediate a broad range of cellular and physiological processes.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 45647651 210 LASIANPHQKLAKRRQLlEAKRERKAAQTLAIITGAFVICWLPFFVMALTMSLCKECEIHTAVASLFLWLGYFNSTLNPV 289
Cdd:cd15048 205 LPASQNPSRARSQREQV-KLRRDRKAAKSLAILVLVFLICWAPYTILTIIRSFCSGSCVDSYLYEFTFWLLWTNSAINPF 283

                        90
                ....*....|...
gi 45647651 290 IYTIFNPEFRRAF 302
Cdd:cd15048 284 LYAACHPRFRKAF 296

D1A (or D1) subtype dopamine receptor, member of the class A family of seven-transmembrane G protein-coupled receptors; Dopamine receptors are members of the class A G protein-coupled receptors that are involved in many neurological processes in the central nervous system (CNS). The neurotransmitter dopamine is the primary endogenous agonist for dopamine receptors. Dopamine receptors consist of at least five subtypes: D1, D2, D3, D4, and D5. The D1 and D5 subtypes are members of the D1-like family of dopamine receptors, whereas the D2, D3 and D4 subtypes are members of the D2-like family. The D1-like family receptors are coupled to G proteins of the G(s) family, which activate adenylate cyclase, causing cAMP formation and activation of protein kinase A. Dopamine receptors are major therapeutic targets for neurological and psychiatric disorders such as drug abuse, depression, schizophrenia, or Parkinson's disease.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 45647651 230 KRERKAAQTLAIITGAFVICWLPFFVMALTMSLCKECE-----IHTAVASLFLWLGYFNSTLNPVIYTiFNPEFRRAF 302
Cdd:cd15320 243 KRETKVLKTLSVIMGVFVCCWLPFFILNCMVPFCKPTStepfcISSTTFDVFVWFGWANSSLNPIIYA-FNADFRKAF 319

muscarinic acetylcholine receptor subtype M3, member of the class A family of seven-transmembrane G protein-coupled receptors; Muscarinic acetylcholine receptors (mAChRs) regulate the activity of many fundamental central and peripheral functions. The mAChR family consists of 5 subtypes M1-M5, which can be further divided into two major groups according to their G-protein coupling preference. The M1, M3 and M5 receptors selectively interact with G proteins of the G(q/11) family, whereas the M2 and M4 receptors preferentially link to the G(i/o) types of G proteins. The M3 receptor is mainly located in smooth muscle, exocrine glands and vascular endothelium. It induces vomiting in the central nervous system and is a critical regulator of glucose homeostasis by modulating insulin secretion. Generally, M3 receptor causes contraction of smooth muscle resulting in vasoconstriction and increased glandular secretion. All GPCRs have a common structural architecture comprising of seven-transmembrane (TM) alpha-helices interconnected by three extracellular and three intracellular loops. A general feature of GPCR signaling is agonist-induced conformational changes in the receptors, leading to activation of the heterotrimeric G proteins, which consist of the guanine nucleotide-binding G-alpha subunit and the dimeric G-beta-gamma subunits. The activated G proteins then bind to and activate numerous downstream effector proteins, which generate second messengers that mediate a broad range of cellular and physiological processes.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 45647651 228 EAKRERKAAQTLAIITGAFVICWLPFFVMALTMSLCKECeIHTAVASLFLWLGYFNSTLNPVIYTIFNPEFRRAFKRILF 307
Cdd:cd15299 192 ETIKEKKAAQTLSAILLAFIITWTPYNIMVLVNTFCDSC-IPKTYWNLGYWLCYINSTVNPVCYALCNKTFRTTFKMLLL 270

muscarinic acetylcholine receptor GAR-2 and similar proteins, member of the class A family of seven-transmembrane G protein-coupled receptors; Muscarinic acetylcholine receptors (mAChRs) regulate the activity of many fundamental central and peripheral functions. The mAChR family consists of 5 subtypes M1-M5, which can be further divided into two major groups according to their G-protein coupling preference. The M1, M3 and M5 receptors selectively interact with G proteins of the G(q/11) family, whereas the M2 and M4 receptors preferentially link to the G(i/o) types of G proteins. Activation of mAChRs by agonist (acetylcholine) leads to a variety of biochemical and electrophysiological responses. In general, the exact nature of these responses and the subsequent physiological effects mainly depend on the molecular and pharmacological identity of the activated receptor subtype(s). All GPCRs have a common structural architecture comprising of seven-transmembrane (TM) alpha-helices interconnected by three extracellular and three intracellular loops. A general feature of GPCR signaling is agonist-induced conformational changes in the receptors, leading to activation of the heterotrimeric G proteins, which consist of the guanine nucleotide-binding G-alpha subunit and the dimeric G-beta-gamma subunits. The activated G proteins then bind to and activate numerous downstream effector proteins, which generate second messengers that mediate a broad range of cellular and physiological processes.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*
gi 45647651 229 AKRERKAAQTLAIITGAFVICWLPFFVMALTMSLCKECE-IHTAVASLFLWLGYFNSTLNPVIYTIFNPEFRRAF 302
Cdd:cd15302 192 ANRARKALRTITFILGAFVICWTPYHILATIYGFCEAPPcVNETLYTISYYLCYMNSPINPFCYALANQQFKKTF 266

beta-1 adrenergic receptors (adrenoceptors), member of the class A family of seven-transmembrane G protein-coupled receptors; The beta-1 adrenergic receptor (beta-1 adrenoceptor), also known as beta-1 AR, is activated by adrenaline (epinephrine) and plays important roles in regulating cardiac function and heart rate. The human heart contains three subtypes of the beta AR: beta-1 AR, beta-2 AR, and beta-3 AR. Beta-1 AR and beta-2 AR, which expressed at about a ratio of 70:30, are the major subtypes involved in modulating cardiac contractility and heart rate by positively stimulating the G(s) protein-adenylate cyclase-cAMP-PKA signaling pathway. In contrast, beta-3 AR produces negative inotropic effects by activating inhibitory G(i) proteins. The aberrant expression of betrayers can lead to cardiac dysfunction such as arrhythmias or heart failure.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 45647651 207 GGVLASIANPHQKLAKRRQLLEAKRERKAAQTLAIITGAFVICWLPFFVMALTMSLCKECeIHTAVASLFLWLGYFNSTL 286
Cdd:cd15958 205 GRFHNTLTGLGRKCKRRPSRILALREQKALKTLGIIMGVFTLCWLPFFLVNVVNVFNREL-VPDWLFVFFNWLGYANSAF 283

                        90
                ....*....|....*.
gi 45647651 287 NPVIYTiFNPEFRRAF 302
Cdd:cd15958 284 NPIIYC-RSPDFRKAF 298

serotonin receptor subtype 2B, member of the class A family of seven-transmembrane G protein-coupled receptors; The 5-HT2 receptors are a subfamily of serotonin receptors that bind the neurotransmitter serotonin (5HT; 5-hydroxytryptamine) in the central nervous system (CNS). The 5-HT2 subfamily is composed of three subtypes that mediate excitatory neurotransmission: 5-HT2A, 5-HT2B, and 5-HT2C. They are selectively linked to G proteins of the G(q/11) family and activate phospholipase C, which leads to activation of protein kinase C and calcium release. In the CNS, serotonin is involved in the regulation of appetite, mood, sleep, cognition, learning and memory, as well as implicated in diseases such as migraine, schizophrenia, and depression. Indeed, 5-HT2 receptors are attractive targets for a variety of psychoactive drugs, ranging from atypical antipsychotic drugs, antidepressants, and anxiolytics, which have an antagonistic action on 5-HT2 receptors, to hallucinogens, which act as agonists at postsynaptic 5-HT2 receptors. All GPCRs have a common structural architecture comprising of seven-transmembrane (TM) alpha-helices interconnected by three extracellular and three intracellular loops. A general feature of GPCR signaling is agonist-induced conformational changes in the receptors, leading to activation of the heterotrimeric G proteins, which consist of the guanine nucleotide-binding G-alpha subunit and the dimeric G-beta-gamma subunits. The activated G proteins then bind to and activate numerous downstream effector proteins, which generate second messengers that mediate a broad range of cellular and physiological processes.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 45647651 223 RRQLLeaKRERKAAQTLAIITGAFVICWLPFFVMALTMSLCKEC--EIHTAVASLFLWLGYFNSTLNPVIYTIFNPEFRR 300
Cdd:cd15306 191 RKQTI--TNEQRASKVLGIVFFLFLLMWCPFFITNITSVLCDSCnqTTLQMLMEIFVWIGYVSSGVNPLVYTLFNKTFRD 268

                ....
gi 45647651 301 AFKR 304
Cdd:cd15306 269 AFGR 272

muscarinic acetylcholine receptor subtype M1, member of the class A family of seven-transmembrane G protein-coupled receptors; Muscarinic acetylcholine receptors (mAChRs) regulate the activity of many fundamental central and peripheral functions. The mAChR family consists of 5 subtypes M1-M5, which can be further divided into two major groups according to their G-protein coupling preference. The M1, M3 and M5 receptors selectively interact with G proteins of the G(q/11) family, whereas the M2 and M4 receptors preferentially link to the G(i/o) types of G proteins. Activation of mAChRs by agonist (acetylcholine) leads to a variety of biochemical and electrophysiological responses. M1 is the dominant mAChR subtype involved in learning and memory. It is linked to synaptic plasticity, neuronal excitability, and neuronal differentiation during early development. All GPCRs have a common structural architecture comprising of seven-transmembrane (TM) alpha-helices interconnected by three extracellular and three intracellular loops. A general feature of GPCR signaling is agonist-induced conformational changes in the receptors, leading to activation of the heterotrimeric G proteins, which consist of the guanine nucleotide-binding G-alpha subunit and the dimeric G-beta-gamma subunits. The activated G proteins then bind to and activate numerous downstream effector proteins, which generate second messengers that mediate a broad range of cellular and physiological processes.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*
gi 45647651 228 EAKRERKAAQTLAIITGAFVICWLPFFVMALTMSLCKECeIHTAVASLFLWLGYFNSTLNPVIYTIFNPEFRRAF 302
Cdd:cd17790 189 ETIKEKKAARTLSAILLAFILTWTPYNIMVLVSTFCKDC-VPKTLWELGYWLCYVNSTVNPMCYALCNKSFRDTF 262

adenosine receptor subfamily, member of the class A family of seven-transmembrane G protein-coupled receptors; The adenosine receptors (or P1 receptors), a family of G protein-coupled purinergic receptors, bind adenosine as their endogenous ligand. There are four types of adenosine receptors in human, designated as A1, A2A, A2B, and A3. Each type is encoded by a different gene and has distinct functions with some overlap. For example, both A1 and A2A receptors are involved in regulating myocardial oxygen consumption and coronary blood flow in the heart, while the A2A receptor also has a broad spectrum of anti-inflammatory effects in the body. These two receptors also expressed in the brain, where they have important roles in the release of other neurotransmitters such as dopamine and glutamate, while the A2B and A3 receptors found primarily in the periphery and play important roles in inflammation and immune responses. The A1 and A3 receptors preferentially interact with G proteins of the G(i/o) family, thereby lowering the intracellular cAMP levels, whereas the A2A and A2B receptors interact with G proteins of the G(s) family, activating adenylate cyclase to elevate cAMP levels.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 45647651 230 KRERKAAQTLAIITGAFVICWLPFFVMALTMSLCKECEIHtavASLFLW---LGYFNSTLNPVIYTIFNPEFRRAF 302
Cdd:cd14968 213 QKEVKAAKSLAIILFLFALCWLPLHIINCITLFCPECKVP---KILTYIailLSHANSAVNPIVYAYRIRKFRQTF 285

trace amine-associated receptor 5, member of the class A family of seven-transmembrane G protein-coupled receptors; The trace amine-associated receptor 5 is one of the 15 identified amine-activated G protein-coupled receptors (TAARs), a distinct subfamily within the class A G protein-coupled receptors. Trace amines are endogenous amines of unknown function that have strong structural and metabolic similarity to classical monoamine neurotransmitters (serotonin, noradrenaline, adrenaline, dopamine, and histamine), which play critical roles in human and animal physiological activities such as cognition, consciousness, mood, motivation, perception, and autonomic responses. However, trace amines are found in the mammalian brain at very low concentrations compared to classical monoamines. Trace amines, including p-tyramine, beta-phenylethylamine, and tryptamine, are also thought to act as chemical messengers to exert their biological effects in vertebrates. All GPCRs have a common structural architecture comprising of seven-transmembrane (TM) alpha-helices interconnected by three extracellular and three intracellular loops. A general feature of GPCR signaling is agonist-induced conformational changes in the receptors, leading to activation of the heterotrimeric G proteins, which consist of the guanine nucleotide-binding G-alpha subunit and the dimeric G-beta-gamma subunits. The activated G proteins then bind to and activate numerous downstream effector proteins, which generate second messengers that mediate a broad range of cellular and physiological processes.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|...
gi 45647651 229 AKRERKAAQTLAIITGAFVICWLPFFVMALTMSLCKECeIHTAVASLFLWLGYFNSTLNPVIYTIFNPEFRRA 301
Cdd:cd15318 210 SKRERKAAKTLGIAVGVYLLCWLPFTIDTMVDSLLNFI-TPPLLFDIIIWFAYFNSACNPLIYVFSYPWFRKA 281

cholecystokinin receptors and related proteins, member of the class A family of seven-transmembrane G protein-coupled receptors; This group represents four G-protein coupled receptors that are members of the RFamide receptor family, including cholecystokinin receptors (CCK-AR and CCK-BR), orexin receptors (OXR), neuropeptide FF receptors (NPFFR), and pyroglutamylated RFamide peptide receptor (QRFPR). These RFamide receptors are activated by their endogenous peptide ligands that share a common C-terminal arginine (R) and an amidated phenylanine (F) motif. CCK-AR (type A, alimentary; also known as CCK1R) is found abundantly on pancreatic acinar cells and binds only sulfated CCK-peptides with very high affinity, whereas CCK-BR (type B, brain; also known as CCK2R), the predominant form in the brain and stomach, binds CCK or gastrin and discriminates poorly between sulfated and non-sulfated peptides. CCK is implicated in regulation of digestion, appetite control, and body weight, and is involved in neurogenesis via CCK-AR. There is some evidence to support that CCK and gastrin, via their receptors, are involved in promoting cancer development and progression, acting as growth and invasion factors. Orexins (OXs; also referred to as hypocretins) are neuropeptide hormones that regulate the sleep-wake cycle and potently influence homeostatic systems regulating appetite and feeding behavior or modulating emotional responses such as anxiety or panic. OXs are synthesized as prepro-orexin (PPO) in the hypothalamus and then proteolytically cleaved into two forms of isoforms: orexin-A (OX-A) and orexin-B (OX-B). OXA is a 33 amino-acid peptide with N-terminal pyroglutamyl residue and two intramolecular disulfide bonds, whereas OXB is a 28 amino-acid linear peptide with no disulfide bonds. OX-A binds orexin receptor 1 (OX1R) with high-affinity, but also binds with somewhat low-affinity to OX2R, and signals primarily to Gq coupling, whereas OX-B shows a strong preference for the orexin receptor 2 (OX2R) and signals through Gq or Gi/o coupling. The 26RFa, also known as QRFP (Pyroglutamylated RFamide peptide), is a 26-amino acid residue peptide that exerts similar orexigenic activity including the regulation of feeding behavior in mammals. It is the ligand for G-protein coupled receptor 103 (GPR103), which is predominantly expressed in paraventricular (PVN) and ventromedial (VMH) nuclei of the hypothalamus. GPR103 shares significant protein sequence homology with orexin receptors (OX1R and OX2R), which have recently shown to produce a neuroprotective effect in Alzheimer's disease by forming a functional heterodimer with GPR103. Neuropeptide FF (NPFF) is a mammalian octapeptide that has been implicated in a wide range of physiological functions in the brain including pain sensitivity, insulin release, food intake, memory, blood pressure, and opioid-induced tolerance and hyperalgesia. The effects of NPFF are mediated through neuropeptide FF1 and FF2 receptors (NPFF1-R and NPFF2-R) which are predominantly expressed in the brain. NPFF induces pro-nociceptive effects, mainly through the NPFF1-R, and anti-nociceptive effects, mainly through the NPFF2-R.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*
gi 45647651 233 RKAAQTLAIITGAFVICWLPFFVMAL-----TMSLCKECEIHTAVASLFLWLGYFNSTLNPVIYTIFNPEFRRAF 302
Cdd:cd14993 222 KKVARMLIVVVVLFALSWLPYYVLSIlldfgPLSSEESDENFLLILPFAQLLGYSNSAINPIIYCFMSKKFRRGF 296

opioid receptors and related proteins, member of the class A family of seven-transmembrane G protein-coupled receptors; This group includes opioid receptors, somatostatin receptors, melanin-concentrating hormone receptors (MCHRs), and neuropeptides B/W receptors. Together they constitute the opioid receptor-like family, members of the class A G-protein coupled receptors. Opioid receptors are coupled to inhibitory G proteins of the G(i/o) family and are involved in regulating a variety of physiological functions such as pain, addiction, mood, stress, epileptic seizure, and obesity, among many others. G protein-coupled somatostatin receptors (SSTRs), which display strong sequence similarity with opioid receptors, binds somatostatin (somatotropin release inhibiting factor), a polypeptide hormone that regulates a wide variety of physiological functions such as neurotransmission, cell proliferation, contractility of smooth muscle cells, and endocrine signaling as well as inhibition of the release of many secondary hormones. MCHR binds melanin concentrating hormone and is presumably involved in the neuronal regulation of food intake. Despite strong homology with somatostatin receptors, MCHR does not appear to bind somatostatin. Neuropeptides B/W receptors are primarily expressed in the CNS and stimulate the cortisol secretion by activating the adenylate cyclase- and the phospholipase C-dependent signaling pathways.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 45647651 210 LASIANPHQKLAKRRqlleAKRERKAAQTLAIITGAFVICWLPF--FVMALTMSLCKECEIHTAVASLFLWLGYFNSTLN 287
Cdd:cd14970 192 LRSSRNLSTSGAREK----RRARRKVTRLVLVVVAVFVVCWLPFhvFQIVRLLIDPPETLTVVGVFLFCIALSYANSCLN 267

                        90
                ....*....|....*
gi 45647651 288 PVIYTIFNPEFRRAF 302
Cdd:cd14970 268 PILYAFLDENFRKSF 282

muscarinic acetylcholine receptor DM1, member of the class A family of seven-transmembrane G protein-coupled receptors; This subgroup includes muscarinic acetylcholine receptor DM1-like from invertebrates. Muscarinic acetylcholine receptors (mAChRs) regulate the activity of many fundamental central and peripheral functions. The mAChR family consists of 5 subtypes M1-M5, which can be further divided into two major groups according to their G-protein coupling preference. The M1, M3 and M5 receptors selectively interact with G proteins of the G(q/11) family, whereas the M2 and M4 receptors preferentially link to the G(i/o) types of G proteins. Activation of mAChRs by agonist (acetylcholine) leads to a variety of biochemical and electrophysiological responses. In general, the exact nature of these responses and the subsequent physiological effects mainly depend on the molecular and pharmacological identity of the activated receptor subtype(s). All GPCRs have a common structural architecture comprising of seven-transmembrane (TM) alpha-helices interconnected by three extracellular and three intracellular loops. A general feature of GPCR signaling is agonist-induced conformational changes in the receptors, leading to activation of the heterotrimeric G proteins, which consist of the guanine nucleotide-binding G-alpha subunit and the dimeric G-beta-gamma subunits. The activated G proteins then bind to and activate numerous downstream effector proteins, which generate second messengers that mediate a broad range of cellular and physiological processes.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 45647651 222 KRRQlleAKRERKAAQTLAIITGAFVICWLPFFVMAL--TMSLCKECeIHTAVASLFLWLGYFNSTLNPVIYTIFNPEFR 299
Cdd:cd15301 192 KKRQ---KKQESKAAKTLSAILLAFIVTWTPYNVLVLikAFFPCSDT-IPTELWDFSYYLCYINSTINPLCYALCNAAFR 267

                ...
gi 45647651 300 RAF 302
Cdd:cd15301 268 RTY 270

muscarinic acetylcholine receptor subtype M2, member of the class A family of seven-transmembrane G protein-coupled receptors; Muscarinic acetylcholine receptors (mAChRs) regulate the activity of many fundamental central and peripheral functions. The mAChR family consists of 5 subtypes M1-M5, which can be further divided into two major groups according to their G-protein coupling preference. The M1, M3 and M5 receptors selectively interact with G proteins of the G(q/11) family, whereas the M2 and M4 receptors preferentially link to the G(i/o) types of G proteins. Activation of M2 receptor causes a decrease in cAMP production, generally leading to inhibitory-type effects. This causes an outward current of potassium in the heart, resulting in a decreased heart rate. All GPCRs have a common structural architecture comprising of seven-transmembrane (TM) alpha-helices interconnected by three extracellular and three intracellular loops. A general feature of GPCR signaling is agonist-induced conformational changes in the receptors, leading to activation of the heterotrimeric G proteins, which consist of the guanine nucleotide-binding G-alpha subunit and the dimeric G-beta-gamma subunits. The activated G proteins then bind to and activate numerous downstream effector proteins, which generate second messengers that mediate a broad range of cellular and physiological processes.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....
gi 45647651 229 AKRERKAAQTLAIITGAFVICWLPFFVMALTMSLCKECeIHTAVASLFLWLGYFNSTLNPVIYTIFNPEFRRAF 302
Cdd:cd15297 190 SSREKKVTRTILAILLAFIITWTPYNVMVLINTFCASC-IPNTVWTIGYWLCYINSTINPACYALCNATFKKTF 262

type 2 opsins in animals, member of the class A family of seven-transmembrane G protein-coupled receptors; This rhodopsin family represents the type 2 opsins found in vertebrates and invertebrates except sponge. Type 2 opsins primarily function as G protein coupled receptors and are responsible for vision as well as for circadian rhythm and pigment regulation. On the contrary, type 1 opsins such as bacteriorhodopsin and proteorhodopsin are found in both prokaryotic and eukaryotic microbes, functioning as light-gated ion channels, proton pumps, sensory receptors and in other unknown functions. Although these two opsin types share seven-transmembrane domain topology and a conserved lysine reside in the seventh helix, type 1 opsins do not activate G-proteins and are not evolutionarily related to type 2. Type 2 opsins can be classified into six distinct subfamilies including the vertebrate opsins/encephalopsins, the G(o) opsins, the G(s) opsins, the invertebrate G(q) opsins, the photoisomerases, and the neuropsins.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|...
gi 45647651 230 KRERKAAQTLAIITGAFVICWLPFFVMALTMSLCKECEIHTAVASLFLWLGYFNSTLNPVIYTIFNPEFRRAF 302
Cdd:cd14969 212 KAEKKVAKMVLVMIVAFLIAWTPYAVVSLYVSFGGESTIPPLLATIPALFAKSSTIYNPIIYVFMNKQFRRAL 284

vasopressin and oxytocin receptors, member of the class A family of seven-transmembrane G protein-coupled receptors; Vasopressin (also known as arginine vasopressin or anti-diuretic hormone) and oxytocin are synthesized in the hypothalamus and are released from the posterior pituitary gland. The actions of vasopressin are mediated by the interaction of this hormone with three receptor subtypes: V1aR, V1bR, and V2R. These subtypes are differ in localization, function, and signaling pathways. Activation of V1aR and V1bR stimulate phospholipase C, while activation of V2R stimulates adenylate cyclase. Although vasopressin and oxytocin differ only by two amino acids and stimulate the same cAMP/PKA pathway, they have divergent physiological functions. Vasopressin is involved in regulating blood pressure and the balance of water and sodium ions, whereas oxytocin plays an important role in the uterus during childbirth and in lactation.

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gi 45647651 237 QTLAIITgAFVICWLPFFVMALTMSLCKECEIHTAVASLFLWLGYFNSTLNPVIYTIFNPEFRRAF 302
Cdd:cd15196 200 LTLVVVA-CYIVCWTPFFVVQMWAAWDPTAPIEGPAFVIIMLLASLNSCTNPWIYLAFSGNLRRAL 264