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Title
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Inherent asymmetry of the structure of F1-ATPase from bovine heart mitochondria at 6.5 A resolution.
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Authors
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J.P.Abrahams,
R.Lutter,
R.J.Todd,
M.J.van Raaij,
A.G.Leslie,
J.E.Walker.
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Ref.
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Embo J, 1993,
12,
1775-1780.
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PubMed id
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Abstract
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ATP synthase, the assembly which makes ATP in mitochondria, chloroplasts and
bacteria, uses transmembrane proton gradients generated by respiration or
photosynthesis to drive the phosphorylation of ADP. Its membrane domain is
joined by a slender stalk to a peripheral catalytic domain, F1-ATPase. This
domain is made of five subunits with stoichiometries of 3 alpha: 3 beta: 1
gamma: 1 delta: 1 epsilon, and in bovine mitochondria has a molecular mass of
371,000. We have determined the 3-dimensional structure of bovine mitochondrial
F1-ATPase to 6.5 A resolution by X-ray crystallography. It is an approximately
spherical globule 110 A in diameter, on a 40 A stem which contains two
alpha-helices in a coiled-coil. This stem is presumed to be part of the stalk
that connects F1 with the membrane domain in the intact ATP synthase. A pit next
to the stem penetrates approximately 35 A into the F1 particle. The stem and the
pit are two examples of the many asymmetric features of the structure. The
central element in the asymmetry is the longer of the two alpha-helices in the
stem, which extends for 90 A through the centre of the assembly and emerges on
top into a dimple 15 A deep. Features with threefold and sixfold symmetry,
presumed to be parts of homologous alpha and beta subunits, are arranged around
the central rod and pit, but the overall structure is asymmetric. The central
helix provides a possible mechanism for transmission of conformational changes
induced by the proton gradient from the stalk to the catalytic sites of the
enzyme.
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