1am4
COMPLEX BETWEEN CDC42HS.GMPPNP AND P50 RHOGAP (H. SAPIENS)COMPLEX BETWEEN CDC42HS.GMPPNP AND P50 RHOGAP (H. SAPIENS)
Structural highlights
Function[RHG01_HUMAN] GTPase activator for the Rho, Rac and Cdc42 proteins, converting them to the putatively inactive GDP-bound state. Cdc42 seems to be the preferred substrate. [CDC42_HUMAN] Plasma membrane-associated small GTPase which cycles between an active GTP-bound and an inactive GDP-bound state. In active state binds to a variety of effector proteins to regulate cellular responses. Involved in epithelial cell polarization processes. Regulates the bipolar attachment of spindle microtubules to kinetochores before chromosome congression in metaphase. Plays a role in the extension and maintenance of the formation of thin, actin-rich surface projections called filopodia. Mediates CDC42-dependent cell migration.[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 PubMedSmall G proteins transduce signals from plasma-membrane receptors to control a wide range of cellular functions. These proteins are clustered into distinct families but all act as molecular switches, active in their GTP-bound form but inactive when GDP-bound. The Rho family of G proteins, which includes Cdc42Hs, activate effectors involved in the regulation of cytoskeleton formation, cell proliferation and the JNK signalling pathway. G proteins generally have a low intrinsic GTPase hydrolytic activity but there are family-specific groups of GTPase-activating proteins (GAPs) that enhance the rate of GTP hydrolysis by up to 10(5) times. We report here the crystal structure of Cdc42Hs, with the non-hydrolysable GTP analogue GMPPNP, in complex with the GAP domain of p50rhoGAP at 2.7A resolution. In the complex Cdc42Hs interacts, mainly through its switch I and II regions, with a shallow pocket on rhoGAP which is lined with conserved residues. Arg 85 of rhoGAP interacts with the P-loop of Cdc42Hs, but from biochemical data and by analogy with the G-protein subunit G(i alpha1), we propose that it adopts a different conformation during the catalytic cycle which enables it to stabilize the transition state of the GTP-hydrolysis reaction. Crystal structure of a small G protein in complex with the GTPase-activating protein rhoGAP.,Rittinger K, Walker PA, Eccleston JF, Nurmahomed K, Owen D, Laue E, Gamblin SJ, Smerdon SJ Nature. 1997 Aug 14;388(6643):693-7. PMID:9262406[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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