Conserved Protein Domain Family
PX_SNX27

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cd06886: PX_SNX27 
The phosphoinositide binding Phox Homology domain of Sorting Nexin 27
The PX domain is a phosphoinositide (PI) binding module present in many proteins with diverse functions. Sorting nexins (SNXs) make up the largest group among PX domain containing proteins. They are involved in regulating membrane traffic and protein sorting in the endosomal system. The PX domain of SNXs binds PIs and targets the protein to PI-enriched membranes. SNXs differ from each other in PI-binding specificity and affinity, and the presence of other protein-protein interaction domains, which help determine subcellular localization and specific function in the endocytic pathway. SNX27 contains an N-terminal PDZ domain followed by a PX domain and a Ras-Associated (RA) domain. It binds G protein-gated potassium (Kir3) channels, which play a role in neuronal excitability control, through its PDZ domain. SNX27 downregulates Kir3 channels by promoting their movement in the endosome, reducing surface expression and increasing degradation. SNX27 also associates with 5-hydroxytryptamine type 4 receptor (5-HT4R), cytohesin associated scaffolding protein (CASP), and diacylglycerol kinase zeta, and may play a role in their intracellular trafficking and endocytic recycling. The SNX27 PX domain preferentially binds to phosphatidylinositol-3-phosphate (PI3P) and is important for targeting to the early endosome.
Statistics
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PSSM-Id: 132796
View PSSM: cd06886
Aligned: 11 rows
Threshold Bit Score: 183.381
Threshold Setting Gi: 219460910
Created: 11-Jul-2008
Updated: 17-Jan-2013
Structure
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Aligned Rows:
 
phosphoinosit..
Feature 1:phosphoinositide binding site [chemical binding site]
Evidence:
  • Comment:A majority of PX domain containing proteins binds phosphatidylinositol-3-phosphate (PI3P) at this site. In some cases, other phosphoinositides, such as PI4P or PI(3,4)P2, are the preferred substrates.
  • Comment:based on the structures of phosphatidylinositol-3-phosphate bound to other members of this superfamily
  • Comment:Two basic residues are key in binding with phosphoinositides: one forms hydrogen bonds with the 3-phosphate of PI(3)P and another forms hydrogen bonds with the 4-and 5-hydroxyl groups of PI(3)P.

Sequence Alignment
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Format: Row Display: Color Bits: Type Selection:
                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
Feature 1                                                      ###                      ##       
gi 71897057  148 KQAVPISIPTYKHVEQNGE------KFVVYNVYMAG----RQLCSKRYREFAILHQNLKREFANFTFPRLPGKWPFSLSE 217
gi 24639936  165 KRSLPISIPDYGIVNRNGE------RYIVFNIHMAG----RQLCSRRYREFANLHSLLRKEFSGFNFPKLPGKWPFQLSE 234
gi 41054611  165 KQAVPISVPTYKHVEQSGE------KFVVYNVYMAG----RQLCSKRYREFAILHQNLKREFANFAFPKLPGKWPFSLSE 234
gi 166200309 158 KQAVPISVPTYKHVEQNGE------KFVVYNVYMAG----RQLCSKRYREFAILHQNLKREFANFTFPRLPGKWPFSLSE 227
gi 148224419 145 KQAVPISIPTYKHVEQNGE------KFVVYNVYMAG----RQLCSKRYREFAILNQNLKREFANFTFPRLPGKWPFSLSE 214
gi 115767153 138 KRPVPITIPDYQHITSDGE------KYVVYNVYMAG----RLLCSHRYSEFANVHAKLKREFIDYQFPKFPGKWPFTLSD 207
gi 75018681  166 NRSLPVTIPSYNTVQDSLE------RYTVFNIHMAG----RQLGSRRYSEFVELHLALKKHFYDYCFPQLPGKWPFKLSE 235
gi 215504551 153 KRSLPISIPDYNWLERSGD------KFVVYNIYMAG----RHLCSRRYREFSVLHVNLRKEFPDFSFPKLPGKWPFSLSD 222
gi 219460910 313 RKLVPTEFPHNLYIQNYTTaa---sTCIALRKWLFDlqreLQLTHLDMANTFFYWQTLKREFPEFPFPKMPGKWPFSLSE 389
gi 156402858 104 NQQQHKAKKQFKNYLIAGFvfisipFVTVYNIYYSG----KQICSKRYKEFSNLHSQLKKEFRDFQFPKFPGKWPFTLSE 179
gi 198435642 131 IRRIEIDIPEYEHVEEEGS------KFVVYCIHLKG----KLVMKRRYSEFLLMYEELMKIFVEFDYPKFPSKKLFQLSE 200
                         90       100       110
                 ....*....|....*....|....*....|....*.
Feature 1             #                              
gi 71897057  218 QQLDARRRGLEEYLEKVCSIRVIGESDIMQEFLSES 253
gi 24639936  235 QQLDTRRRGLEQYLEKVCAVRVIAESDAVQDFLTDT 270
gi 41054611  235 QQLDARRRGLEEYLEKVCSVRVIGESDIMQEFLSES 270
gi 166200309 228 QQLDARRRGLEEYLEKVCSIRVIGESDIMQEFLSES 263
gi 148224419 215 QQLDARRRGLEEYLEKVCSIRIIGESDIMQEFLSES 250
gi 115767153 208 QQLDTRRRSLEHYIEKVSAVRAIGESDIMRDFLSTE 243
gi 75018681  236 QQLDSRRRGLEQYLEKICTIRVIAESELVQKFLMEC 271
gi 215504551 223 QQLDARRRGLEQYLEKVCAIRVIAESDTMQDFLTDM 258
gi 219460910 390 QQLDARRRGLEQYLEKVCSIRVIAESDVMQEFLADI 425
gi 156402858 180 HQLEARRKGLESYLQQVCSVFVIGDSVLMQDFLDDD 215
gi 198435642 201 QQLERRRSMLETFIQETFKRRVIQECDIVMDFLKIE 236

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