1aqg
From Proteopedia
NMR STRUCTURE OF THE RHODOPSIN-BOUND C-TERMINAL PEPTIDE OF THE TRANSDUCIN ALPHA-SUBUNIT, 20 STRUCTURES
Overview
A large superfamily of transmembrane receptors control cellular responses to diverse extracellular signals by catalyzing activation of specific types of heterotrimeric GTP-binding proteins. How these receptors recognize and promote nucleotide exchange on G protein alpha subunits to initiate signal amplification is unknown. The three-dimensional structure of the transducin (Gt) alpha subunit C-terminal undecapeptide Gtalpha(340-350) IKENLKDCGLF was determined by transferred nuclear Overhauser effect spectroscopy while it was bound to photoexcited rhodopsin. Light activation of rhodopsin causes a dramatic shift from a disordered conformation of Gtalpha(340-350) to a binding motif with a helical turn followed by an open reverse turn centered at Gly-348, a helix-terminating C capping motif of an alphaL type. Docking of the NMR structure to the GDP-bound x-ray structure of Gt reveals that photoexcited rhodopsin promotes the formation of a continuous helix over residues 325-346 terminated by the C-terminal helical cap with a unique cluster of crucial hydrophobic side chains. A molecular mechanism by which activated receptors can control G proteins through reversible conformational changes at the receptor-G protein interface is demonstrated.
About this Structure
1AQG is a Single protein structure of sequence from Bos taurus. Full crystallographic information is available from OCA.
Reference
Light-activated rhodopsin induces structural binding motif in G protein alpha subunit., Kisselev OG, Kao J, Ponder JW, Fann YC, Gautam N, Marshall GR, Proc Natl Acad Sci U S A. 1998 Apr 14;95(8):4270-5. PMID:9539726 Page seeded by OCA on Fri May 2 10:35:14 2008
