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The 2.2 A crystal structure of transducin-alpha complexed with GTP gamma S.


Noel JPJ P , Hamm HE H E , Sigler PB P B . Nature. 1993 12 16; 366(6456). 654-63


The 2.2 A crystal structure of activated rod transducin, Gt alpha.GTP gamma S, shows the bound GTP gamma S molecule occluded deep in a cleft between a domain structurally homologous to small GTPases and a helical domain unique to heterotrimeric G proteins. The structure, when combined with biochemical and genetic studies, suggests: how an activated receptor might open this cleft to allow nucleotide exchange; a mechanism for GTP-induced changes in effector and receptor binding surfaces; and a mechanism for GTPase activity not evident from previous data.