2p0f
ArhGAP9 PH domain in complex with Ins(1,3,5)P3
Structural highlights
FunctionRHG09_HUMAN GTPase activator for the Rho-type GTPases by converting them to an inactive GDP-bound state. Has a substantial GAP activity toward CDC42 and RAC1 and less toward RHOA. Has a role in regulating adhesion of hematopoietic cells to the extracellular matrix.[1] 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 PubMedPleckstrin homology (PH) domains are phosphoinositide (PI)-binding modules that target proteins to membrane surfaces. Here we define a family of PH domain proteins, including Tiam1 and ArhGAP9, that demonstrates specificity for PI(4,5)P(2), as well as for PI(3,4,5)P(3) and PI(3,4)P(2), the products of PI 3-kinase. These PH domain family members utilize a non-canonical phosphoinositide binding pocket related to that employed by beta-spectrin. Crystal structures of the PH domain of ArhGAP9 in complex with the headgroups of Ins(1,3,4)P(3), Ins(1,4,5)P(3), and Ins(1,3,5)P(3) reveal how two adjacent phosphate positions in PI(3,4)P(2), PI(4,5)P(2), and PI(3,4,5)P(3) are accommodated through flipped conformations of the bound phospholipid. We validate the non-canonical site of phosphoinositide interaction by showing that binding pocket mutations, which disrupt phosphoinositide binding in vitro, also disrupt membrane localization of Tiam1 in cells. We posit that the diversity in PI interaction modes displayed by PH domains contributes to their versatility of use in biological systems. Non-canonical interaction of phosphoinositides with pleckstrin homology domains of Tiam1 and ArhGAP9.,Ceccarelli DF, Blasutig IM, Goudreault M, Li Z, Ruston J, Pawson T, Sicheri F J Biol Chem. 2007 May 4;282(18):13864-74. Epub 2007 Mar 5. PMID:17339315[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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