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PDBsum entry 6itc
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Protein transport
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PDB id
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6itc
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Contents |
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765 a.a.
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420 a.a.
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58 a.a.
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116 a.a.
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43 a.a.
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225 a.a.
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112 a.a.
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References listed in PDB file
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Key reference
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Title
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Structure of the substrate-Engaged seca-Secy protein translocation machine.
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Authors
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C.Ma,
X.Wu,
D.Sun,
E.Park,
M.A.Catipovic,
T.A.Rapoport,
N.Gao,
L.Li.
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Ref.
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Nat Commun, 2019,
10,
2872.
[DOI no: ]
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PubMed id
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Abstract
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The Sec61/SecY channel allows the translocation of many proteins across the
eukaryotic endoplasmic reticulum membrane or the prokaryotic plasma membrane. In
bacteria, most secretory proteins are transported post-translationally through
the SecY channel by the SecA ATPase. How a polypeptide is moved through the
SecA-SecY complex is poorly understood, as structural information is lacking.
Here, we report an electron cryo-microscopy (cryo-EM) structure of a
translocating SecA-SecY complex in a lipid environment. The translocating
polypeptide chain can be traced through both SecA and SecY. In the captured
transition state of ATP hydrolysis, SecA's two-helix finger is close to the
polypeptide, while SecA's clamp interacts with the polypeptide in a
sequence-independent manner by inducing a short β-strand. Taking into account
previous biochemical and biophysical data, our structure is consistent with a
model in which the two-helix finger and clamp cooperate during the ATPase cycle
to move a polypeptide through the channel.
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