6bc1
From Proteopedia
A Complex between PH Domain of p190RhoGEF and Activated Rac1 Bound to a GTP Analog
Structural highlights
Function[RAC1_HUMAN] Plasma membrane-associated small GTPase which cycles between active GTP-bound and inactive GDP-bound states. In its active state, binds to a variety of effector proteins to regulate cellular responses such as secretory processes, phagocytosis of apoptotic cells, epithelial cell polarization and growth-factor induced formation of membrane ruffles. Rac1 p21/rho GDI heterodimer is the active component of the cytosolic factor sigma 1, which is involved in stimulation of the NADPH oxidase activity in macrophages (By similarity). Essential for the SPATA13-mediated regulation of cell migration and adhesion assembly and disassembly. Stimulates PKN2 kinase activity. In concert with RAB7A, plays a role in regulating the formation of RBs (ruffled borders) in osteoclasts. In glioma cells, promotes cell migration and invasion.[1] [2] [3] [4] [5] Isoform B has an accelerated GEF-independent GDP/GTP exchange and an impaired GTP hydrolysis, which is restored partially by GTPase-activating proteins. It is able to bind to the GTPase-binding domain of PAK but not full-length PAK in a GTP-dependent manner, suggesting that the insertion does not completely abolish effector interaction.[6] [7] [8] [9] [10] [ARG28_HUMAN] Functions as a RHOA-specific guanine nucleotide exchange factor regulating signaling pathways downstream of integrins and growth factor receptors. Functions in axonal branching, synapse formation and dendritic morphogenesis. Functions also in focal adhesion formation, cell motility and B-lymphocytes activation. May regulate NEFL expression and aggregation and play a role in apoptosis (By similarity). Publication Abstract from PubMedRho family GTPases regulate a wide range of cellular processes. This includes cellular dynamics where three subfamilies, Rho, Rac, and Cdc42, are known to regulate cell shape and migration though coordinate action. Activation of Rho proteins largely depends on Rho Guanine nucleotide Exchange Factors (RhoGEFs) through a catalytic Dbl homology (DH) domain linked to a pleckstrin homology (PH) domain that subserves various functions. The PH domains from Lbc RhoGEFs, which specifically activate RhoA, have been shown to bind to activated RhoA. Here, p190RhoGEF is shown to also bind Rac1.GTP. Crystal structures reveal that activated Rac1 and RhoA use their effector-binding surfaces to associate with the same hydrophobic surface on the PH domain. Both activated RhoA and Rac1 can stimulate exchange of nucleotide on RhoA by localization of p190RhoGEF to its substrate, RhoA.GDP, in vitro. The binding of activated RhoA provides a mechanism for positive feedback regulation as previously proposed for the family of Lbc RhoGEFs. In contrast, the novel interaction between activated Rac1 and p190RhoGEF reveals a potential mechanism for cross-talk regulation where Rac can directly effect stimulation of RhoA. The greater capacity of Rac1 to stimulate p190RhoGEF among the Lbc RhoGEFs suggests functional specialization. Direct regulation of p190RhoGEF by activated Rho and Rac GTPases.,Dada O, Gutowski S, Brautigam CA, Chen Z, Sternweis PC J Struct Biol. 2017 Nov 28. pii: S1047-8477(17)30210-1. doi:, 10.1016/j.jsb.2017.11.014. PMID:29196061[11] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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