The structure of the G protein heterotrimer Gi alpha 1 beta 1 gamma 2.
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.
Wall
M A
MA
Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas 75235, USA.
Coleman
D E
DE
Lee
E
E
Iñiguez-Lluhi
J A
JA
Posner
B A
BA
Gilman
A G
AG
Sprang
S R
SR
D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D002460:Cell Line; D018360:Crystallography, X-Ray; D019204:GTP-Binding Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D006153:Guanosine Diphosphate / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D051381:Rats; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification; D016415:Sequence Alignment; D015398:Signal Transduction; D018411:Spodoptera
D011994:Recombinant Proteins; D006153:Guanosine Diphosphate; D019204:GTP-Binding Proteins