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Site of G protein binding to rhodopsin mapped with synthetic peptides from the alpha subunit.


Hamm HEH E , Deretic D D , Arendt A A , Hargrave PA P A , Koenig B B , Hofmann KP K P . Science (New York, N.Y.). 1988 8 12; 241(4867). 832-5


The interaction between receptors and guanine nucleotide binding (G) proteins leads to G protein activation and subsequent regulation of effector enzymes. The molecular basis of receptor-G protein interaction has been examined by using the ability of the G protein from rods (transducin) to cause a conformational change in rhodopsin as an assay. Synthetic peptides corresponding to two regions near the carboxyl terminus of the G protein alpha subunit, Glu311-Val328 and Ile340-Phe350, compete with G protein for interaction with rhodopsin. Amino acid substitution studies show that Cys321 is required for this effect. Ile340-Phe350 and a modified peptide, acetyl-Glu311-Lys329-amide, mimic G protein effects on rhodopsin conformation, showing that these peptides bind to and stabilize the activated conformation of rhodopsin.