1aqg
From Proteopedia
NMR STRUCTURE OF THE RHODOPSIN-BOUND C-TERMINAL PEPTIDE OF THE TRANSDUCIN ALPHA-SUBUNIT, 20 STRUCTURES
Structural highlights
FunctionGNAT1_BOVIN Guanine nucleotide-binding proteins (G proteins) are involved as modulators or transducers in various transmembrane signaling systems. Transducin is an amplifier and one of the transducers of a visual impulse that performs the coupling between rhodopsin and cGMP-phosphodiesterase. Publication Abstract from PubMedA 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. 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[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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