The structure of the G protein heterotrimer Gi alpha 1 beta 1 gamma 2.

Wall MA, Coleman DE, Lee E, IƱiguez-Lluhi JA, Posner BA, Gilman AG, Sprang SR
Cell. 1995 83 (6): 1047-58

PMID: 8521505 · DOI:10.1016/0092-8674(95)90220-1

The crystallographic structure of the G protein heterotrimer Gi alpha 1(GDP)beta 1 gamma 2 (at 2.3 A) reveals two nonoverlapping regions of contact between alpha and beta, an extended interface between beta and nearly all of gamma, and limited interaction of alpha with gamma. The major alpha/beta interface covers switch II of alpha, and GTP-induced rearrangement of switch II causes subunit dissociation during signaling. Alterations in GDP binding in the heterotrimer (compared with alpha-GDP) explain stabilization of the inactive conformation of alpha by beta gamma. Repeated WD motifs in beta form a circularized sevenfold beta propeller. The conserved cores of these motifs are a scaffold for display of their more variable linkers on the exterior face of each propeller blade.

MeSH Terms (15)

Amino Acid Sequence Animals Cattle Cell Line Crystallography, X-Ray GTP-Binding Proteins Guanosine Diphosphate Models, Molecular Molecular Sequence Data Protein Conformation Rats Recombinant Proteins Sequence Alignment Signal Transduction Spodoptera

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