1AQG: NMR STRUCTURE OF THE RHODOPSIN-BOUND C-TERMINAL PEPTIDE OF THE TRANSDUCIN ALPHA-SUBUNIT, 20 STRUCTURES

Citation:
Abstract
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.
PDB ID: 1AQGDownload
MMDB ID: 47952
PDB Deposition Date: 1997/7/29
Updated in MMDB: 2007/10
Experimental Method:
solution nmr
Source Organism:
Similar Structures:
Molecular Components in 1AQG
Label Count Molecule
Protein (1 molecule)
1
Transducin Alpha-1 Subunit(Gene symbol: GNAT1)
Molecule annotation
* Click molecule labels to explore molecular sequence information.

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