Conserved Protein Domain Family
PX_PI3K_C2_beta

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cd07290: PX_PI3K_C2_beta 
The phosphoinositide binding Phox Homology Domain of the Beta Isoform of Class II Phosphoinositide 3-Kinases
The PX domain is a phosphoinositide (PI) binding module present in many proteins with diverse functions. The Phosphoinositide 3-Kinase (PI3K) family of enzymes catalyzes the phosphorylation of the 3-hydroxyl group of the inositol ring of phosphatidylinositol. PI3Ks play an important role in a variety of fundamental cellular processes, including cell motility, the Ras pathway, vesicle trafficking and secretion, immune cell activation and apoptosis. PI3Ks are divided into three main classes (I, II, and III) based on their substrate specificity, regulation, and domain structure. Class II PI3Ks preferentially use PI as a substrate to produce PI3P, but can also phosphorylate PI4P to produce PI(3,4)P2. They function as monomers and do not associate with any regulatory subunits. Class II enzymes contain an N-terminal Ras binding domain, a lipid binding C2 domain, a PI3K homology domain of unknown function, an ATP-binding cataytic domain, a PX domain, and a second C2 domain at the C-terminus. The class II beta isoform, PI3K-C2beta, contributes to the migration and survival of cancer cells. It regulates Rac activity and impacts membrane ruffling, cell motility, and cadherin-mediated cell-cell adhesion. The PX domain is involved in targeting of proteins to PI-enriched membranes, and may also be involved in protein-protein interaction.
Statistics
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PSSM-Id: 132823
View PSSM: cd07290
Aligned: 3 rows
Threshold Bit Score: 221.721
Threshold Setting Gi: 47206366
Created: 15-Jan-2009
Updated: 17-Jan-2013
Structure
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Aligned Rows:
 
phosphoinosit..
Feature 1:phosphoinositide binding site [chemical binding site]
Evidence:
  • Comment:The PX domain of PI3K-C2alpha preferentially binds phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2).
  • 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:
Feature 1                                          ###                       ##             #  
O00750    1369 DVFLCRHEKIfhpNKGYIYVVKVMRENTHeATYIQRTFEEFQELHNKLRLLFPSSHLPSFPSRFVIGRsrgeAVAERRRE 1448 human
XP_417956 1360 DVFLCRHERVfnpSKGYTYVVKVKRESPSeVTFVQRTFEEFQELHNKLRLLFPSSLLPSFPSRFIIGRsrgeAVAERRKE 1439 chicken
CAF94954   976 NLYVCRHISTansSKGHAFVVKVQKDGHKeALFVQRTFEEFNELHSKLRLLFPASKLPRFPNRLVIGRss-dATADRRKD 1054 spotted green pu...
Feature 1                                   
O00750    1449 ELNGYIWHLIHAppEVAECDLVYTFFHPL 1477 human
XP_417956 1440 ELNGYIWHLIHAapEVAECDLIYTFFHPL 1468 chicken
CAF94954  1055 ELNAYLWHLINSppEVAQSDLVSTFFHPL 1083 spotted green pufferfish

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