1FQK: Crystal Structure Of The Heterodimeric Complex Of The Rgs Domain Of Rgs9, And The Gt/i1 Chimera Alpha Subunit [(rgs9)-(gt/i1alpha)-(gdp)- (alf4-)-(mg2+)]

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.
PDB ID: 1FQKDownload
MMDB ID: 15597
PDB Deposition Date: 2000/9/5
Updated in MMDB: 2007/10
Experimental Method:
x-ray diffraction
Resolution: 2.3  Å
Source Organism:
Bos taurus
Similar Structures:
Biological Unit for 1FQK: dimeric; determined by author
Molecular Components in 1FQK
Label Count Molecule
Proteins (2 molecules)
Guanine Nucleotide-binding Protein G(t) Subunit Alpha-1, Guanine Nucleotide-binding Protein G(i) Subunit Alpha-1,guanine Nucleotide-binding Protein G(t) Subunit Alpha-1
Molecule annotation
Regulator of G-protein Signaling 9(Gene symbol: RGS9)
Molecule annotation
Chemicals (4 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB