Recognition of the activated states of Galpha13 by the rgRGS domain of PDZRhoGEF

Structure. 2008 Oct 8;16(10):1532-43. doi: 10.1016/j.str.2008.07.009.


G12 class heterotrimeric G proteins stimulate RhoA activation by RGS-RhoGEFs. However, p115RhoGEF is a GTPase Activating Protein (GAP) toward Galpha13, whereas PDZRhoGEF is not. We have characterized the interaction between the PDZRhoGEF rgRGS domain (PRG-rgRGS) and the alpha subunit of G13 and have determined crystal structures of their complexes in both the inactive state bound to GDP and the active states bound to GDP*AlF (transition state) and GTPgammaS (Michaelis complex). PRG-rgRGS interacts extensively with the helical domain and the effector-binding sites on Galpha13 through contacts that are largely conserved in all three nucleotide-bound states, although PRG-rgRGS has highest affinity to the Michaelis complex. An acidic motif in the N terminus of PRG-rgRGS occupies the GAP binding site of Galpha13 and is flexible in the GDP*AlF complex but well ordered in the GTPgammaS complex. Replacement of key residues in this motif with their counterparts in p115RhoGEF confers GAP activity.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • GTP-Binding Protein alpha Subunits, G12-G13 / chemistry*
  • GTP-Binding Protein alpha Subunits, G12-G13 / metabolism*
  • GTPase-Activating Proteins / genetics
  • GTPase-Activating Proteins / metabolism
  • Guanine Nucleotide Exchange Factors / chemistry*
  • Guanine Nucleotide Exchange Factors / genetics
  • Guanine Nucleotide Exchange Factors / metabolism*
  • Guanosine 5'-O-(3-Thiotriphosphate) / metabolism
  • Mice
  • Models, Molecular
  • Molecular Sequence Data
  • Protein Binding
  • Protein Interaction Domains and Motifs
  • Protein Structure, Quaternary
  • Protein Structure, Tertiary
  • RGS Proteins / chemistry
  • Rats
  • Sequence Homology, Amino Acid
  • Substrate Specificity / genetics


  • GTPase-Activating Proteins
  • Guanine Nucleotide Exchange Factors
  • PDZ-RhoGEF, rat
  • RGS Proteins
  • Guanosine 5'-O-(3-Thiotriphosphate)
  • GTP-Binding Protein alpha Subunits, G12-G13

Associated data

  • PDB/3CX6
  • PDB/3CX7
  • PDB/3CX8