Conserved Protein Domain Family
PX_SNX3

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cd07293: PX_SNX3 
The phosphoinositide binding Phox Homology domain of Sorting Nexin 3
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. SNX3 associates with early endosomes through a PX domain-mediated interaction with phosphatidylinositol-3-phosphate (PI3P). It associates with the retromer complex, a membrane coat multimeric complex required for endosomal retrieval of lysosomal hydrolase receptors to the Golgi, and functions as a cargo-specific adaptor for the retromer. SNX3 is required for the formation of multivesicular bodies, which function as transport intermediates to late endosomes. It also promotes cell surface expression of the amiloride-sensitive epithelial Na+ channel (ENaC), which is critical in sodium homeostasis and maintenance of extracellular fluid volume.
Statistics
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PSSM-Id: 132826
View PSSM: cd07293
Aligned: 4 rows
Threshold Bit Score: 252.991
Threshold Setting Gi: 57530297
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:based on the binding of phosphatidylinositol-3-phosphate to yeast SNX3 (Grd19p)
  • 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 12643620   28 FLEIDVSNPQTVGVGRGRFTTYEIRVKTNLPIFKLKESTVRRRYSDFEWLRSELERESKVVVPPLPGKAFLRQLPFRGDD 107
gi 57530297   28 FLEIDVGNPQTVGVGRGRFTTYEIRVKTNLPIFKLKESTVRRRYSDFEWLRNELERESKVVVPPLPGKALLRQLPFRGDD 107
gi 169158121  28 FLEIDVTNPETVGVGRNRFTTYEIKLKTNLPIFKLKESRVRRRYSDFEWLRGELERESKVVVPPLPGKALFRQLPFRGDD 107
gi 148232628  28 FLEIDVRNPQTVGVGRGRFTTYEVRLKTNLPIFKLKESCVRRRYSDFEWLKSELERESKVVVPPLPGKALFRQLPFRGDE 107
                         90       100       110       120
                 ....*....|....*....|....*....|....*....|...
Feature 1         #        #                                
gi 12643620  108 GIFDDNFIEERKQGLEQFINKVAGHPLAQNERCLHMFLQDEII 150
gi 57530297  108 GIFDDSFIEERKQALEQFINKVAGHPLAQNERCLHMFLQDEVI 150
gi 169158121 108 GIFDDSFIEERRQGLEQFLNKVAGHPLAQNERCLHMFLQDESV 150
gi 148232628 108 GIFDDSFIEERKQGLEQFLNKVAGHPLAQNERCLHMFLQDEIL 150

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