Mapping the Gα13 binding interface of the rgRGS domain of p115RhoGEF

Zhe Chen, William D. Singer, Clark D. Wells, Stephen R. Sprang, Paul C. Sternweis

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37 Scopus citations


Structural requirements for function of the Rho GEF (guanine nucleotide exchange factor) regulator of G protein signaling (rgRGS) domains of p115RhoGEF and homologous exchange factors differ from those of the classical RGS domains. An extensive mutagenesis analysis of the p115RhoGEF rgRGS domain was undertaken to determine its functional interface with the Gα13 subunit. Results indicate that there is global resemblance between the interaction surface of the rgRGS domain with Gα13 and the interactions of RGS4 and RGS9 with their Gα substrates. However, there are distinct differences in the distribution of functionally critical residues between these structurally similar surfaces and an additional essential requirement for a cluster of negatively charged residues at the N terminus of rgRGS. Lack of sequence conservation within the N terminus may also explain the lack of GTPase-activating protein (GAP) activity in a subset of the rgRGS domains. For all mutations, loss of functional GAP activity is paralleled by decreases in binding to Gα13. The same mutations, when placed in the context of the p115RhoGEF molecule, produce deficiencies in GAP activity as observed with the rgRGS domain alone but show no attenuation of the regulation of Rho exchange activity by Gα13. This suggests that the rgRGS domain may serve a structural or allosteric role in the regulation of the nucleotide exchange activity of p115RhoGEF on Rho by Gα13.

Original languageEnglish
Pages (from-to)9912-9919
Number of pages8
JournalJournal of Biological Chemistry
Issue number11
StatePublished - Mar 14 2003


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