Light-activated rhodopsin induces structural binding motif in G protein α subunit

Oleg G. Kisselev, Jeff Kao, Jay W. Ponder, Yang C. Fann, N. Gautam, Garland R. Marshall

Research output: Contribution to journalArticlepeer-review

163 Scopus citations


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 α subunits to initiate signal amplification is unknown. The three-dimensional structure of the transducin (Gt) α subunit C-terminal undecapeptide Gtα(340-350) IKENLKDCGLF was determined by transferred nuclear Overhauser effect spectroscopy while it was found to photoexcited rhodopsin. Light activation of rhodopsin causes a dramatic shift from a disordered conformation of Gtα(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 {L) 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.

Original languageEnglish
Pages (from-to)4270-4275
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number8
StatePublished - Apr 14 1998


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