1zsg
From Proteopedia
beta PIX-SH3 complexed with an atypical peptide from alpha-PAK
Structural highlights
FunctionARHG7_HUMAN Acts as a RAC1 guanine nucleotide exchange factor (GEF) and can induce membrane ruffling. Functions in cell migration, attachment and cell spreading. Promotes targeting of RAC1 to focal adhesions (By similarity). May function as a positive regulator of apoptosis. Downstream of NMDA receptors and CaMKK-CaMK1 signaling cascade, promotes the formation of spines and synapses in hippocampal neurons.[1] [2] [3] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe PAK Ser/Thr kinases are important downstream effectors of the Rho family GTPases Cdc42 and Rac, partly mediating the role of these G proteins in cell proliferation and cytoskeletal rearrangements. As well as small G proteins, PAK interacts with the Cdc42/Rac exchange factor beta-PIX via the PIX SH3 domain and a nontypical Pro-rich region in PAK. This interaction is thought to affect the localization of PAK, as well as increased GTP/GDP exchange of Rac and Cdc42. We have determined the structure of the PIX-SH3/PAK peptide complex and shown that it differs from typical Src-like SH3/peptide complexes. The peptide makes contacts through the Pro-rich sequence in a similar way to standard SH3/peptide complexes, even though the Pro residue positions are not conserved. In addition, there are interactions with a Pro and Lys in the PAK, which are C-terminal to the conserved Arg found in all SH3-binding sequences. These contact a fourth binding pocket on the SH3 domain. We have measured the affinity of PIX-SH3 for the PAK peptide and found that it is of intermediate affinity. When PAK is activated, Ser-199 in the PIX-binding site is phosphorylated. This phosphorylation is sufficient to reduce the affinity for PIX 6-fold. Structural analysis of the SH3 domain of beta-PIX and its interaction with alpha-p21 activated kinase (PAK).,Mott HR, Nietlispach D, Evetts KA, Owen D Biochemistry. 2005 Aug 23;44(33):10977-83. PMID:16101281[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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