First immunoglobulin (Ig)-like domain of carcinoembryonic antigen (CEA) related cell adhesion molecule (CEACAM); The members here are composed of the immunoglobulin (Ig)-like domain 1 in carcinoembryonic antigen (CEA) related cell adhesion molecule (CEACAM) proteins. The CEA family is a group of anchored or secreted glycoproteins, expressed by epithelial cells, leukocytes, endothelial cells, and placenta. The CEA family is divided into the CEACAM and pregnancy-specific glycoprotein (PSG) subfamilies. This group represents the CEACAM subfamily. CEACAM1 has many important cellular functions: it is a cell adhesion molecule and a signaling molecule that regulates the growth of tumor cells, an angiogenic factor, and a receptor for bacterial and viral pathogens, including mouse hepatitis virus (MHV). In mice, four isoforms of CEACAM1 generated by alternative splicing have either two (D1, D4) or four (D1-D4) Ig-like domains on the cell surface.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 568945818 156 LSIDPVPRHAAEGGSVLLQVHNLPEDVQTFSWYKGVLSTQDFKIAEYSIATKSIIRGRAHSRREIGYTNGSLLLQDVTEK 235
Cdd:cd05774    1 LTIELVPPQVAEGENVLLLVHNLPENLLAYAWYKGKTVSPNFLIASYIISTNSSTPGPAYSGRETIYPNGSLLIQNVTQK 80

                         90       100
                 ....*....|....*....|....*
gi 568945818 236 DSGLYTLITIDSNVRVVTAHVQVNI 260
Cdd:cd05774   81 DTGFYTLQTITADLQTEQASVHLQV 105

Immunoglobulin (Ig)-like domain of human carcinoembryonic antigen (CEA) related cell adhesion molecule (CEACAM) domains 2, 4, and 6, and similar domains; The members here are composed of the second, fourth, and sixth immunoglobulin (Ig)-like domains in human carcinoembryonic antigen (CEA) related cell adhesion molecule (CEACAM) protein subfamily. The CEA family is a group of anchored or secreted glycoproteins expressed by epithelial cells, leukocytes, endothelial cells, and placenta. The CEA family is divided into the CEACAM and pregnancy-specific glycoprotein (PSG) subfamilies. This group represents the CEACAM subfamily. CEACAM1 has many important cellular functions; it is a cell adhesion molecule and a signaling molecule that regulates the growth of tumor cells, an angiogenic factor, and a receptor for bacterial and viral pathogens, including mouse hepatitis virus (MHV). In mice, four isoforms of CEACAM1 generated by alternative splicing have either two [D1, D4] or four [D1-D4] Ig-like domains on the cell surface.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 568945818 266 QPAMRV-TDSTVRVQSSVVFTCFSDNTGVSIRWLFNNQRLQLTERMTLSPSKCQLRIHTVRKEDAGEYQCEAFNPVSSKT 344
Cdd:cd05740    1 KPFISSnNSNPVEDKDAVTLTCEPETQNTSYLWWFNGQSLPVTPRLTLSNGNRTLTLLNVTREDAGAYQCEISNPVSANR 80

                 ....*....
gi 568945818 345 SLPVSLTVM 353
Cdd:cd05740   81 SDPVTLDVI 89

First immunoglobulin (Ig)-like domain of carcinoembryonic antigen (CEA) related cell adhesion molecule (CEACAM); The members here are composed of the immunoglobulin (Ig)-like domain 1 in carcinoembryonic antigen (CEA) related cell adhesion molecule (CEACAM) proteins. The CEA family is a group of anchored or secreted glycoproteins, expressed by epithelial cells, leukocytes, endothelial cells, and placenta. The CEA family is divided into the CEACAM and pregnancy-specific glycoprotein (PSG) subfamilies. This group represents the CEACAM subfamily. CEACAM1 has many important cellular functions: it is a cell adhesion molecule and a signaling molecule that regulates the growth of tumor cells, an angiogenic factor, and a receptor for bacterial and viral pathogens, including mouse hepatitis virus (MHV). In mice, four isoforms of CEACAM1 generated by alternative splicing have either two (D1, D4) or four (D1-D4) Ig-like domains on the cell surface.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 568945818 156 LSIDPVPRHAAEGGSVLLQVHNLPEDVQTFSWYKGVLSTQDFKIAEYSIATKSIIRGRAHSRREIGYTNGSLLLQDVTEK 235
Cdd:cd05774    1 LTIELVPPQVAEGENVLLLVHNLPENLLAYAWYKGKTVSPNFLIASYIISTNSSTPGPAYSGRETIYPNGSLLIQNVTQK 80

                         90       100
                 ....*....|....*....|....*
gi 568945818 236 DSGLYTLITIDSNVRVVTAHVQVNI 260
Cdd:cd05774   81 DTGFYTLQTITADLQTEQASVHLQV 105

Immunoglobulin (Ig)-like domain of human carcinoembryonic antigen (CEA) related cell adhesion molecule (CEACAM) domains 2, 4, and 6, and similar domains; The members here are composed of the second, fourth, and sixth immunoglobulin (Ig)-like domains in human carcinoembryonic antigen (CEA) related cell adhesion molecule (CEACAM) protein subfamily. The CEA family is a group of anchored or secreted glycoproteins expressed by epithelial cells, leukocytes, endothelial cells, and placenta. The CEA family is divided into the CEACAM and pregnancy-specific glycoprotein (PSG) subfamilies. This group represents the CEACAM subfamily. CEACAM1 has many important cellular functions; it is a cell adhesion molecule and a signaling molecule that regulates the growth of tumor cells, an angiogenic factor, and a receptor for bacterial and viral pathogens, including mouse hepatitis virus (MHV). In mice, four isoforms of CEACAM1 generated by alternative splicing have either two [D1, D4] or four [D1-D4] Ig-like domains on the cell surface.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 568945818 266 QPAMRV-TDSTVRVQSSVVFTCFSDNTGVSIRWLFNNQRLQLTERMTLSPSKCQLRIHTVRKEDAGEYQCEAFNPVSSKT 344
Cdd:cd05740    1 KPFISSnNSNPVEDKDAVTLTCEPETQNTSYLWWFNGQSLPVTPRLTLSNGNRTLTLLNVTREDAGAYQCEISNPVSANR 80

                 ....*....
gi 568945818 345 SLPVSLTVM 353
Cdd:cd05740   81 SDPVTLDVI 89

Immunoglobulin like; IG domains that cannot be classified into one of IGv1, IGc1, IGc2, IG.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 568945818   275 TVRVQSSVVFTC-FSDNTGVSIRWLFNNQR-LQLTERMTLSPSKCQ--LRIHTVRKEDAGEYQCEAFNPVSSKTSlPVSL 350
Cdd:smart00410   5 TVKEGESVTLSCeASGSPPPEVTWYKQGGKlLAESGRFSVSRSGSTstLTISNVTPEDSGTYTCAATNSSGSASS-GTTL 83

                   ..
gi 568945818   351 TV 352
Cdd:smart00410  84 TV 85

Immunoglobulin I-set domain;

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 568945818  273 DSTVRVQSSVVFTCfsDNTGV---SIRWLFNNQRLQLTER--MTLSPSKCQLRIHTVRKEDAGEYQCEAFNPVSSKTSlP 347
Cdd:pfam07679   9 DVEVQEGESARFTC--TVTGTpdpEVSWFKDGQPLRSSDRfkVTYEGGTYTLTISNVQPDDSGKYTCVATNSAGEAEA-S 85

                  ....*
gi 568945818  348 VSLTV 352
Cdd:pfam07679  86 AELTV 90

First immunoglobulin (Ig)-like domain of carcinoembryonic antigen (CEA) related cell adhesion molecule (CEACAM); The members here are composed of the immunoglobulin (Ig)-like domain 1 in carcinoembryonic antigen (CEA) related cell adhesion molecule (CEACAM) proteins. The CEA family is a group of anchored or secreted glycoproteins, expressed by epithelial cells, leukocytes, endothelial cells, and placenta. The CEA family is divided into the CEACAM and pregnancy-specific glycoprotein (PSG) subfamilies. This group represents the CEACAM subfamily. CEACAM1 has many important cellular functions: it is a cell adhesion molecule and a signaling molecule that regulates the growth of tumor cells, an angiogenic factor, and a receptor for bacterial and viral pathogens, including mouse hepatitis virus (MHV). In mice, four isoforms of CEACAM1 generated by alternative splicing have either two (D1, D4) or four (D1-D4) Ig-like domains on the cell surface.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 568945818 156 LSIDPVPRHAAEGGSVLLQVHNLPEDVQTFSWYKGVLSTQDFKIAEYSIATKSIIRGRAHSRREIGYTNGSLLLQDVTEK 235
Cdd:cd05774    1 LTIELVPPQVAEGENVLLLVHNLPENLLAYAWYKGKTVSPNFLIASYIISTNSSTPGPAYSGRETIYPNGSLLIQNVTQK 80

                         90       100
                 ....*....|....*....|....*
gi 568945818 236 DSGLYTLITIDSNVRVVTAHVQVNI 260
Cdd:cd05774   81 DTGFYTLQTITADLQTEQASVHLQV 105

Immunoglobulin (Ig)-like domain of human carcinoembryonic antigen (CEA) related cell adhesion molecule (CEACAM) domains 2, 4, and 6, and similar domains; The members here are composed of the second, fourth, and sixth immunoglobulin (Ig)-like domains in human carcinoembryonic antigen (CEA) related cell adhesion molecule (CEACAM) protein subfamily. The CEA family is a group of anchored or secreted glycoproteins expressed by epithelial cells, leukocytes, endothelial cells, and placenta. The CEA family is divided into the CEACAM and pregnancy-specific glycoprotein (PSG) subfamilies. This group represents the CEACAM subfamily. CEACAM1 has many important cellular functions; it is a cell adhesion molecule and a signaling molecule that regulates the growth of tumor cells, an angiogenic factor, and a receptor for bacterial and viral pathogens, including mouse hepatitis virus (MHV). In mice, four isoforms of CEACAM1 generated by alternative splicing have either two [D1, D4] or four [D1-D4] Ig-like domains on the cell surface.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 568945818 266 QPAMRV-TDSTVRVQSSVVFTCFSDNTGVSIRWLFNNQRLQLTERMTLSPSKCQLRIHTVRKEDAGEYQCEAFNPVSSKT 344
Cdd:cd05740    1 KPFISSnNSNPVEDKDAVTLTCEPETQNTSYLWWFNGQSLPVTPRLTLSNGNRTLTLLNVTREDAGAYQCEISNPVSANR 80

                 ....*....
gi 568945818 345 SLPVSLTVM 353
Cdd:cd05740   81 SDPVTLDVI 89

Immunoglobulin (Ig)-like domain of carcinoembryonic antigen (CEA) related cell adhesion molecule (CEACAM) and similar proteins; The members here are composed of the immunoglobulin (Ig)-like domain in carcinoembryonic antigen (CEA) related cell adhesion molecule (CEACAM) and related domains. The CEA family is a group of anchored or secreted glycoproteins, expressed by epithelial cells, leukocytes, endothelial cells and placenta. The CEA family is divided into the CEACAM and pregnancy-specific glycoprotein (PSG) subfamilies. This group represents the CEACAM subfamily. CEACAM1 has many important cellular functions: it is a cell adhesion molecule and a signaling molecule that regulates the growth of tumor cells, an angiogenic factor, and a receptor for bacterial and viral pathogens, including mouse hepatitis virus (MHV). In mice, four isoforms of CEACAM1 generated by alternative splicing have either two (D1, D4) or four (D1-D4) Ig-like domains on the cell surface. This family corresponds to the D1 Ig-like domain. Also belonging to this group is the N-terminal immunoglobulin (Ig)-like domain of the signaling lymphocyte activation molecule (SLAM) family, CD84-like family. The SLAM family is a group of immune-cell specific receptors that can regulate both adaptive and innate immune responses. SLAM family proteins are organized as an extracellular domain with having two or four Ig-like domains, a single transmembrane segment, and a cytoplasmic region having Tyr-based motifs. The extracellular domain is organized as a membrane-distal Ig variable (IgV) domain that is responsible for ligand recognition and a membrane-proximal truncated Ig constant-2 (IgC2) domain.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 568945818 165 AAEGGSVLLQVHNLPEDVQTFSWYKGVLSTQDFKIAEYSIATKSIIRGRAHSRREIGYTNGSLLLQDVTEKDSGLYTLIT 244
Cdd:cd05741    7 GAEGKNVLLLVPNLQTPLKSVSWYKGKQVSRNDEIAEYENSSDEFRAGSAFSGREYIYTNGSLLIQNITLSDTGFYTLES 86

                         90
                 ....*....|....*.
gi 568945818 245 IDSNVRVVTAHVQVNI 260
Cdd:cd05741   87 TNIGGKTESATFQLHV 102

Immunoglobulin domain; The members here are composed of the immunoglobulin (Ig) domain found in the Ig superfamily. The Ig superfamily is a heterogenous group of proteins, built on a common fold comprised of a sandwich of two beta sheets. Members of this group are components of immunoglobulin, neuroglia, cell surface glycoproteins, including T-cell receptors, CD2, CD4, CD8, and membrane glycoproteins, including butyrophilin and chondroitin sulfate proteoglycan core protein. A predominant feature of most Ig domains is a disulfide bridge connecting the two beta-sheets with a tryptophan residue packed against the disulfide bond. Ig superfamily (IgSF) domains can be divided into 4 main classes based on their structures and sequences: the Variable (V), Constant 1 (C1), Constant 2 (C2), and Intermediate (I) sets. Typically, the V-set domains have A, B, E, and D strands in one sheet and A', G, F, C, C' and C" in the other. The structures in C1-set are smaller than those in the V-set; they have one beta sheet that is formed by strands A, B, E, and D and the other by strands G, F, C, and C'. Moreover, a C1-set Ig domain contains a short C' strand (three residues) and lacks A' and C" strand. Unlike other Ig domain sets, C2-set structures do not have a D strand. Like the V-set Ig domains, members of the I-set have a discontinuous A strand, but lack a C" strand.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 568945818 282 VVFTC-FSDNTGVSIRWLFNNQRLQLT--ERMTLSPSKCQLRIHTVRKEDAGEYQCEAFNPVSSKTS 345
Cdd:cd00096    1 VTLTCsASGNPPPTITWYKNGKPLPPSsrDSRRSELGNGTLTISNVTLEDSGTYTCVASNSAGGSAS 67

Immunoglobulin V-set domain; This domain is found in antibodies as well as neural protein P0 and CTL4 amongst others.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 568945818   44 SVAAGGSILLLVHNIPKY---LQSLFWYKG-LIAFNKVEIARYRTAKNSGEPGPAHSGRETV-YSNGSLLLQNVTWKDTG 118
Cdd:pfam07686   7 TVALGGSVTLPCTYSSSMseaSTSVYWYRQpPGKGPTFLIAYYSNGSEEGVKKGRFSGRGDPsNGDGSLTIQNLTLSDSG 86

                          90       100
                  ....*....|....*....|..
gi 568945818  119 FYTLRTLTRYQKMEFAHIYLQV 140
Cdd:pfam07686  87 TYTCAVIPSGEGVFGKGTRLTV 108

Immunoglobulin domain; This family contains immunoglobulin-like domains.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 568945818  272 TDSTVRVQSSVVFTCFSD-NTGVSIRWLFNNQRL--QLTERMTLSPSKCQLRIHTVRKEDAGEYQCEAFN 338
Cdd:pfam13927   9 SSVTVREGETVTLTCEATgSPPPTITWYKNGEPIssGSTRSRSLSGSNSTLTISNVTRSDAGTYTCVASN 78

agrin-responsive second immunoglobulin-like domains (Ig2) of the Muscle-specific kinase (MuSK) ectodomain; a member of the I-set of Ig superfamily domains; The members here are composed of the second immunoglobulin-like (Ig) domains of the Muscle-specific kinase (MuSK) ectodomain. MuSK is a receptor tyrosine kinase specifically expressed in skeletal muscle, where it plays a central role in the formation and maintenance of the neuromuscular junction (NMJ). MuSK is activated by agrin, a neuron-derived heparan sulfate proteoglycan. The activation of MUSK in myotubes regulates the formation of NMJs through the regulation of different processes including the specific expression of genes in subsynaptic nuclei, the reorganization of the actin cytoskeleton and the clustering of the acetylcholine receptors (AChR) in the postsynaptic membrane. The Ig superfamily (IgSF) is a heterogenous group of proteins, built on a common fold comprised of a sandwich of two beta sheets. IgSF domains can be divided into 4 main classes based on their structures and sequences: the Variable (V), Constant 1 (C1), Constant 2 (C2), and Intermediate (I) sets. Unlike the V-set, one of the distinctive features of I-set domains is the lack of a C" strand. The structure of the MuSK lacks this strand and thus it belongs to the I-set of the IgSF. I-set domains are found in several cell adhesion molecules (such as VCAM, ICAM, and MADCAM), and are also present in numerous other diverse protein families, including several tyrosine-protein kinase receptors, the hemolymph protein hemolin, the muscle proteins titin, telokin, and twitchin, the neuronal adhesion molecule axonin-1, and the signaling molecule semaphorin 4D that is involved in axonal guidance, immune function and angiogenesis.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 568945818 264 VTQPAMRVTdstVRVQSSVVFTCFS-DNTGVSIRWLFNNQRLQLTERMTLSPSKcQLRIHTVRKEDAGEYQCEAFNPVSS 342
Cdd:cd20968    2 ITRPPTNVT---IIEGLKAVLPCTTmGNPKPSVSWIKGDDLIKENNRIAVLESG-SLRIHNVQKEDAGQYRCVAKNSLGI 77

                         90
                 ....*....|
gi 568945818 343 KTSLPVSLTV 352
Cdd:cd20968   78 AYSKPVTIEV 87

N-terminal immunoglobulin (Ig)-like domain of T-cell surface antigen CD2, and similar domains; The members here are composed of the N-terminal immunoglobulin (Ig)-like domain (or domain 1) of T-cell surface antigen Clusters of Differentiation (CD) 2 and similar proteins. CD2 is a T-cell specific surface glycoprotein and is critically important for mediating adhesion between T cells and antigen-presenting cells or between cytolytic T cells and target cells. CD2 is located on chromosome 1 at 1p13 in humans and on chromosome 3 in mice. CD2 contains an extracellular domain with two or Ig-like domains, a single transmembrane segment, and a cytoplasmic region rich in proline and basic residues.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 568945818 165 AAEGGSVLLQVHNLPEDVQTFSWYKGvlstqDFKIAEYSIATKSIIRGRAHSRREIGYTNGSLLLQDVTEKDSGLYTL-I 243
Cdd:cd05775    7 GALGGNVTLTISSLQDDIDEIKWKKT-----KDKIVEWENNIGPTYFGSFKDRVLLDKESGSLTIKNLTKEDSGTYELeI 81

                 ....*.
gi 568945818 244 TIDSNV 249
Cdd:cd05775   82 TSTNGK 87

Fourth immunoglobulin (Ig)-like domain in Robo (roundabout) receptors; member of the I-set of Ig superfamily (IgSF) domains; Members here are composed the fourth immunoglobulin (Ig)-like domain in Robo (roundabout) receptors. Robo receptors play a role in the development of the central nervous system (CNS), and are receptors of Slit protein. Slit is a repellant secreted by the neural cells in the midline. Slit acts through Robo to prevent most neurons from crossing the midline from either side. Three mammalian Robo homologs (Robo1, Robo2, Robo3), and three mammalian Slit homologs (Slit-1, Slit-2, Slit-3), have been identified. Commissural axons, which cross the midline, express low levels of Robo; longitudinal axons, which avoid the midline, express high levels of Robo. Robo1, Robo2, and Robo3 are expressed by commissural neurons in the vertebrate spinal cord and Slit-1, Slit-2, and Slit-3 are expressed at the ventral midline. Robo-3 is a divergent member of the Robo family which instead of being a positive regulator of Slit responsiveness, antagonizes Slit responsiveness in precrossing axons. The Slit-Robo interaction is mediated by the second leucine-rich repeat (LRR) domain of Slit and the two N-terminal Ig domains of Robo, Ig1 and Ig2. The primary Robo binding site for Slit2 has been shown by surface plasmon resonance experiments and mutational analysis to be the Ig1 domain, while the Ig2 domain has been proposed to harbor a weak secondary binding site. This group belongs to the I-set of IgSF domains, having A-B-E-D strands in one beta-sheet and A'-G-F-C-C' in the other. Like the V-set Ig domains, members of the I-set have a discontinuous A strand, but lack a C" strand.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 568945818 262 QLVTQPamrvTDSTVRVQSSVVFTCFSD-NTGVSIRW--------LFNNQRLQLTERMTLSPSKcQLRIHTVRKEDAGEY 332
Cdd:cd05726    1 QFVVKP----RDQVVALGRTVTFQCETKgNPQPAIFWqkegsqnlLFPYQPPQPSSRFSVSPTG-DLTITNVQRSDVGYY 75

                         90
                 ....*....|
gi 568945818 333 QCEAFNPVSS 342
Cdd:cd05726   76 ICQALNVAGS 85

Fourth Ig domain of the neural cell adhesion molecule contactin-2, and similar domains; The members here are composed of the fourth Ig domain of the neural cell adhesion molecule contactin-2. Contactins are comprised of six Ig domains followed by four fibronectin type III (FnIII) domains anchored to the membrane by glycosylphosphatidylinositol. Contactin-2 (also called TAG-1, axonin-1) facilitates cell adhesion by homophilic binding between molecules in apposed membranes. The first four Ig domains form the intermolecular binding fragment which arranges as a compact U-shaped module by contacts between Ig domains 1 and 4, and domains 2 and 3. It has been proposed that a linear zipper-like array forms, from contactin-2 molecules alternatively provided by the two apposed membranes.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 568945818 271 VTDSTVRVQSSVVFTC-FSDNTGVSIRWLFNNQRLQLTERMTLSPSKcqLRIHTVRKEDAGEYQCEAFN 338
Cdd:cd05728    6 ISDTEADIGSSLRWECkASGNPRPAYRWLKNGQPLASENRIEVEAGD--LRITKLSLSDSGMYQCVAEN 72

IL-beta-binding protein; Provisional

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 568945818 213 RAHSRREIGYTNGSLLLQDVTEKDSGLYTLI---TIDSNVRVVTAHVQVNIHQLVTQPAMRVTDSTV-RVQSSVVFTCFS 288
Cdd:PHA02785 165 RLRNKRLKQRTPGIITIEDVRKNDAGYYTCVlkyIYGDKTYNVTRIVKLEVRDRIIPPTMQLPEGVVtSIGSNLTIACRV 244

                         90       100       110       120       130       140       150       160
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 568945818 289 D----NTGVSIRWLFNNQ-----------RLQLTERMTLSPSK----CQLRIHTVRKEDAGEYQCEAFNPVSSKTSLPVS 349
Cdd:PHA02785 245 SlrppTTDADVFWISNGMyyeeddedgdgRISVANKIYTTDKRrvitSRLNINPVKEEDATTFTCMAFTIPSISKTVTIS 324

                 ..
gi 568945818 350 LT 351
Cdd:PHA02785 325 IT 326

Fifth immunoglobulin domain of the Drosophila melanogaster Dscam protein, and similar domains; a member of the I-set of IgSF domains; The members here are composed of the fifth immunoglobulin domain of the Drosophila melanogaster Down syndrome cell adhesion molecule (DSCAM) protein and similar proteins. Down syndrome cell adhesion molecule (DSCAM) is a cell adhesion molecule that plays critical roles in neural development, including axon guidance and branching, axon target recognition, self-avoidance and synaptic formation. DSCAM belongs to the immunoglobulin superfamily and contributes to defects in the central nervous system in Down syndrome patients. Vertebrate DSCAMs differ from Drosophila Dscam1 in that they lack the extensive alternative splicing that occurs in the insect gene. Drosophila melanogaster Dscam has 38,016 isoforms generated by the alternative splicing of four variable exon clusters, which allows every neuron in the fly to display a distinctive set of Dscam proteins on its cell surface. Drosophila Dscam1 is a cell-surface protein that plays important roles in neural development and axon tiling of neurons. It is shown that thousands of isoforms bind themselves through specific homophilic (self-binding) interactions, a process which mediates cellular self-recognition. Drosophila Dscam2 is also alternatively spliced and plays a key role in the development of two visual system neurons, monopolar cells L1 and L2. This group is a member of the I-set Ig domains, having A-B-E-D strands in one beta-sheet and A'-G-F-C-C' in the other. Like the V-set Ig domains, members of the I-set have a discontinuous A strand but lack a C" strand.

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|....*..
gi 568945818 294 SIRWLFNNQRLQLTERMTLSPSKcQLRIHTV-RKEDAGEYQCEAFNP 339
Cdd:cd20958   31 SITWEKDGRRLPLNHRQRVFPNG-TLVIENVqRSSDEGEYTCTARNQ 76

Second immunoglobulin (Ig)-like domain of fibroblast growth factor (FGF) receptor_like-1(FGFRL1); member of the I-set of IgSF domains; The members here are composed of the second immunoglobulin (Ig)-like domain of fibroblast growth factor (FGF) receptor like-1(FGFRL1). FGFRL1 is comprised of a signal peptide, three extracellular Ig-like modules, a transmembrane segment, and a short intracellular domain. FGFRL1 is expressed preferentially in skeletal tissues. Similar to FGF receptors, the expressed protein interacts specifically with heparin and with FGF2. FGFRL1 does not have a protein tyrosine kinase domain at its C-terminus; neither does its cytoplasmic domain appear to interact with a signaling partner. It has been suggested that FGFRL1 may not have any direct signaling function, but instead acts as a decoy receptor trapping FGFs and preventing them from binding other receptors.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 568945818 265 TQPA-MRVTDSTVRVQSSVVFTCF-SDNTGVSIRWLFNNQRLQLTERMTLSPSKCQLRIHTVRKEDAGEYQCEAFNPV 340
Cdd:cd05856    4 TQPAkMRRRVIARPVGSSVRLKCVaSGNPRPDITWLKDNKPLTPPEIGENKKKKWTLSLKNLKPEDSGKYTCHVSNRA 81

Immunoglobulin domain; This family contains immunoglobulin-like domains.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 568945818  155 QLSIDPVPRHAAEGGSVLL--QVHNLPEDvqTFSWYKGvlstqdfkiaeysiatKSIIRGRAHSRREIGYTNGSLLLQDV 232
Cdd:pfam13927   3 VITVSPSSVTVREGETVTLtcEATGSPPP--TITWYKN----------------GEPISSGSTRSRSLSGSNSTLTISNV 64

                  ....*....
gi 568945818  233 TEKDSGLYT 241
Cdd:pfam13927  65 TRSDAGTYT 73

Third immunoglobulin (Ig)-like domain in Robo (roundabout) receptors; member of the I-set of Ig superfamily (IgSF) domains; The members here are composed of the third immunoglobulin (Ig)-like domain in Robo (roundabout) receptors. Robo receptors play a role in the development of the central nervous system (CNS), and are receptors of Slit protein. Slit is a repellant secreted by the neural cells in the midline. Slit acts through Robo to prevent most neurons from crossing the midline from either side. Three mammalian Robo homologs (Robo1, Robo2, Robo3), and three mammalian Slit homologs (Slit-1,Slit-2, Slit-3), have been identified. Commissural axons, which cross the midline, express low levels of Robo; longitudinal axons, which avoid the midline, express high levels of Robo. Robo1, Robo2, and Robo3 are expressed by commissural neurons in the vertebrate spinal cord and Slit-1, Slit-2, and Slit-3 are expressed at the ventral midline. Robo-3 is a divergent member of the Robo family which instead of being a positive regulator of Slit responsiveness, antagonizes Slit responsiveness in precrossing axons. The Slit-Robo interaction is mediated by the second leucine-rich repeat (LRR) domain of Slit and the two N-terminal Ig domains of Robo, Ig1 and Ig2. The primary Robo binding site for Slit2 has been shown by surface plasmon resonance experiments and mutational analysis to be the Ig1 domain, while the Ig2 domain has been proposed to harbor a weak secondary binding site. This group belongs to the I-set of IgSF domains, having A-B-E-D strands in one beta-sheet and A'-G-F-C-C' in the other. Like the V-set Ig domains, members of the I-set have a discontinuous A strand, but lack a C" strand.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 568945818 273 DSTVRVQSSVVFTCFSDNTGV-SIRWLFNNQRLQLTeRMTLSPSKcQLRIHTVRKEDAGEYQCEAFNPVsSKTSLPVSLT 351
Cdd:cd05725    6 NQVVLVDDSAEFQCEVGGDPVpTVRWRKEDGELPKG-RYEILDDH-SLKIRKVTAGDMGSYTCVAENMV-GKIEASATLT 82

                 .
gi 568945818 352 V 352
Cdd:cd05725   83 V 83

IL-1 receptor-like protein; Provisional

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 568945818 219 EIGYTNGSLLLQDVTEKDSGLYtLITIDSNVRVVTAHVQVNIHQ-LVTQPAMRVTDSTVRVQSSVVF-TCFSDNTgvsIR 296
Cdd:PHA02826  92 EIGDRSENLWIGNVINIDEGIY-ICTISSGNICEESTIRLTFDSgTINYQFNSGKDSKLHCYGTDGIsSTFKDYT---LT 167

                         90       100       110
                 ....*....|....*....|....*....|....*...
gi 568945818 297 WLFNNQRLQLTERMTLSPSKCQLRIHTVRKEDAGEYQC 334
Cdd:PHA02826 168 WYKNGNIVLYTDRIQLRNNNSTLVIKSATHDDSGIYTC 205