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Nat Struct Mol Biol. 2005 Feb;12(2):191-7. Epub 2005 Jan 16.

Structure of the p115RhoGEF rgRGS domain-Galpha13/i1 chimera complex suggests convergent evolution of a GTPase activator.

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Department of Biochemistry, The University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390, USA.


p115RhoGEF, a guanine nucleotide exchange factor (GEF) for Rho GTPase, is also a GTPase-activating protein (GAP) for G12 and G13 heterotrimeric Galpha subunits. The GAP function of p115RhoGEF resides within the N-terminal region of p115RhoGEF (the rgRGS domain), which includes a module that is structurally similar to RGS (regulators of G-protein signaling) domains. We present here the crystal structure of the rgRGS domain of p115RhoGEF in complex with a chimera of Galpha13 and Galphai1. Two distinct surfaces of rgRGS interact with Galpha. The N-terminal betaN-alphaN hairpin of rgRGS, rather than its RGS module, forms intimate contacts with the catalytic site of Galpha. The interface between the RGS module of rgRGS and Galpha is similar to that of a Galpha-effector complex, suggesting a role for the rgRGS domain in the stimulation of the GEF activity of p115RhoGEF by Galpha13.

[Indexed for MEDLINE]

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