Structural determinants for regulation of phosphodiesterase by a G protein at 2.0 A

Nature. 2001 Feb 22;409(6823):1071-7. doi: 10.1038/35059138.


A multitude of heptahelical receptors use heterotrimeric G proteins to transduce signals to specific effector target molecules. The G protein transducin, Gt, couples photon-activated rhodopsin with the effector cyclic GMP phosophodiesterase (PDE) in the vertebrate phototransduction cascade. The interactions of the Gt alpha-subunit (alpha(t)) with the inhibitory PDE gamma-subunit (PDEgamma) are central to effector activation, and also enhance visual recovery in cooperation with the GTPase-activating protein regulator of G-protein signalling (RGS)-9 (refs 1-3). Here we describe the crystal structure at 2.0 A of rod transducin alpha x GDP x AlF4- in complex with the effector molecule PDEgamma and the GTPase-activating protein RGS9. In addition, we present the independently solved crystal structures of the RGS9 RGS domain both alone and in complex with alpha(t/i1) x GDP x AlF4-. These structures reveal insights into effector activation, synergistic GTPase acceleration, RGS9 specificity and RGS activity. Effector binding to a nucleotide-dependent site on alpha(t) sequesters PDEgamma residues implicated in PDE inhibition, and potentiates recruitment of RGS9 for hydrolytic transition state stabilization and concomitant signal termination.

Publication types

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

MeSH terms

  • 3',5'-Cyclic-GMP Phosphodiesterases / chemistry*
  • 3',5'-Cyclic-GMP Phosphodiesterases / metabolism
  • Amino Acid Sequence
  • Animals
  • Cattle
  • Cloning, Molecular
  • Crystallography, X-Ray
  • Cyclic Nucleotide Phosphodiesterases, Type 6
  • GTP-Binding Proteins / chemistry*
  • GTP-Binding Proteins / metabolism
  • Models, Molecular
  • Molecular Sequence Data
  • Protein Binding
  • Protein Conformation
  • RGS Proteins / chemistry
  • RGS Proteins / metabolism
  • Rod Cell Outer Segment / chemistry
  • Rod Cell Outer Segment / enzymology
  • Sequence Alignment
  • Transducin / chemistry
  • Transducin / metabolism


  • RGS Proteins
  • regulator of g-protein signaling 9
  • 3',5'-Cyclic-GMP Phosphodiesterases
  • Cyclic Nucleotide Phosphodiesterases, Type 6
  • GTP-Binding Proteins
  • Transducin

Associated data

  • PDB/1FQI
  • PDB/1FQJ
  • PDB/1FQK