Functional consequences of G alpha 13 mutations that disrupt interaction with p115RhoGEF

Oncogene. 2005 Mar 24;24(13):2155-65. doi: 10.1038/sj.onc.1208414.


The G-protein alpha subunit, alpha(13), regulates cell growth and differentiation through the monomeric Rho GTPase. Alpha(13) activates Rho through direct stimulation of the guanine nucleotide exchange factor p115RhoGEF, which contains a regulator of G-protein signaling homology domain (RH) in its N-terminus. Through its RH domain, p115RhoGEF also functions as a GAP for G alpha(13). The mechanism for the G alpha(13)/p115RhoGEF interaction is not well understood. Here, we determined specific alpha(13) residues important for its interaction with p115RhoGEF. GST-pulldowns and co-immunoprecipitation assays revealed that individually mutating alpha(13) residues Lys204, Glu229, or Arg232 to opposite charge residues disrupts the interaction of activated alpha(13) with the RH domain of p115RhoGEF or full-length p115RhoGEF. We further demonstrate that mutation of Glu229, and to a lesser extent Lys204 or Arg232, disrupts the ability of activated alpha(13) to induce the recruitment of p115RhoGEF to the plasma membrane (PM) and to activate Rho-mediated serum response element-luciferase gene transcription. Interestingly, an alpha(13) mutant where a conserved Gly was mutated to a Ser (G205S) retained its ability to bind to p115RhoGEF, induce p115RhoGEF recruitment to the PM, and activate Rho-dependent signaling, even though identical Gly to Ser mutations in other alpha disrupt their interaction with regulator of G-protein signaling (RGS) proteins. These results demonstrate that, whereas several features of a typical alpha/RGS interaction are preserved in the alpha(13)/p115RhoGEF interaction, there are also significant differences.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Substitution
  • Arginine
  • Binding Sites
  • Cell Line
  • Cloning, Molecular
  • GTP-Binding Protein alpha Subunits, G12-G13 / genetics*
  • GTP-Binding Protein alpha Subunits, G12-G13 / metabolism*
  • Glutamic Acid
  • Guanine Nucleotide Exchange Factors / metabolism*
  • Humans
  • Kidney
  • Lysine
  • Mutagenesis, Site-Directed
  • Recombinant Fusion Proteins / metabolism
  • Rho Guanine Nucleotide Exchange Factors
  • Transfection


  • Guanine Nucleotide Exchange Factors
  • Recombinant Fusion Proteins
  • Rho Guanine Nucleotide Exchange Factors
  • Glutamic Acid
  • Arginine
  • GTP-Binding Protein alpha Subunits, G12-G13
  • Lysine