RhoGAP_ARHGAP22_24_25: GTPase-activator protein (GAP) domain for Rho-like GTPases found in ARHGAP22, 24 and 25-like proteins; longer isoforms of these proteins contain an additional N-terminal pleckstrin homology (PH) domain. ARHGAP25 (KIA0053) has been identified as a GAP for Rac1 and Cdc42. Short isoforms (without the PH domain) of ARHGAP24, called RC-GAP72 and p73RhoGAP, and of ARHGAP22, called p68RacGAP, has been shown to be involved in angiogenesis and endothelial cell capillary formation. Small GTPases cluster into distinct families, and all act as molecular switches, active in their GTP-bound form but inactive when GDP-bound. The Rho family of GTPases activates effectors involved in a wide variety of developmental processes, including regulation of cytoskeleton formation, cell proliferation and the JNK signaling pathway. GTPases generally have a low intrinsic GTPase hydrolytic activity but there are family-specific groups of GAPs that enhance the rate of GTP hydrolysis by several orders of magnitude.
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