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Title
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The structure of the G protein heterotrimer Gi alpha 1 beta 1 gamma 2.
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Authors
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M.A.Wall,
D.E.Coleman,
E.Lee,
J.A.Iñiguez-Lluhi,
B.A.Posner,
A.G.Gilman,
S.R.Sprang.
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Ref.
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Cell, 1995,
83,
1047-1058.
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PubMed id
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Abstract
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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.
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