Conserved Protein Domain Family
PX_SNX2

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cd07282: PX_SNX2 
The phosphoinositide binding Phox Homology domain of Sorting Nexin 2
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. SNX2 is a component of the retromer complex, a membrane coat multimeric complex required for endosomal retrieval of lysosomal hydrolase receptors to the Golgi. The retromer consists of a cargo-recognition subcomplex and a subcomplex formed by a dimer of sorting nexins (SNX1 and/or SNX2), which ensures efficient cargo sorting by facilitating proper membrane localization of the cargo-recognition subcomplex. Similar to SNX1, SNX2 contains a Bin/Amphiphysin/Rvs (BAR) domain, which detects membrane curvature, C-terminal to the PX domain. The PX domain of SNX2 preferentially binds phosphatidylinositol-3-phosphate (PI3P), but not PI(3,4,5)P3. Studies on mice deficient with SNX1 and/or SNX2 suggest that they provide an essential function in embryogenesis and are functionally redundant.
Statistics
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PSSM-Id: 132815
View PSSM: cd07282
Aligned: 4 rows
Threshold Bit Score: 266.151
Threshold Setting Gi: 83415158
Created: 23-Jan-2009
Updated: 17-Jan-2013
Structure
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Aligned Rows:
 
phosphoinosit..
Feature 1:phosphoinositide binding site [chemical binding site]
Evidence:
  • Comment:SNX1 binds phosphatidylinositol-3-phosphate (PI3P) and PI(3,5)P2, but does not bind PI(3,4,5)P3.
  • 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 110826413 142 IEIGVSDPEKVGDGMNAYMAYRVTTKTSLSMFSKSEFSVKRRFSDFLGLHSKLASKYLHVGYIVPPAPEKSIVGMTKVKV 221
gi 148230456 142 LEIGVSDPEKVGDGMNAYMAYRVTTKTSLSMFNKNEFFVRRRFSDFLGLHSKLATKYMHIGYIVPPAPEKSIVGMTKVKV 221
gi 60302864  141 IEINVSDPEKVGDGMNAYMAYRVTTKTSISMFHRSEFSVKRRFSDFLGLHSKLATKYMHIGYIVPPAPEKSIVGMTKVKV 220
gi 83415158  129 IQISVSDPEKVGDGMNAYMVYKVTTKSCLSVFSRSEVCVRRRFSDFLGLHSKLASKYLHVGLIVPPAPEKSIVGMTKVKV 208
                         90       100       110       120
                 ....*....|....*....|....*....|....*....|....
Feature 1                     #                              
gi 110826413 222 GKEDSSSTEFVEKRRAALERYLQRTVKHPTLLQDPDLRQFLESS 265
gi 148230456 222 GKEDSSSNEFVEKRRAALERYLQRTVKHPTLLQDPDLRQFLESS 265
gi 60302864  221 GKEDSSSTEFVEKRRAALERYLQRTVKHPTLLQDPDLRQFLENS 264
gi 83415158  209 GKEDLSSVEFVEKRRSALERYLMRTVKHPALLKDPDVLQFLESS 252

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