Single copies of Sec61 and TRAP associate with a nontranslating mammalian ribosome.
Structure
; 16(7): 1126-37, 2008 Jul.
Article
em En
| MEDLINE
| ID: mdl-18611385
ABSTRACT
During cotranslational protein translocation, the ribosome associates with a membrane channel, formed by the Sec61 complex, and recruits the translocon-associated protein complex (TRAP). Here we report the structure of a ribosome-channel complex from mammalian endoplasmic reticulum in which the channel has been visualized at 11 A resolution. In this complex, single copies of Sec61 and TRAP associate with a nontranslating ribosome and this stoichiometry was verified by quantitative mass spectrometry. A bilayer-like density surrounds the channel and can be attributed to lipid and detergent. The crystal structure of an archaeal homolog of the Sec61 complex was then docked into the map. In this model, two cytoplasmic loops of Sec61 may interact with RNA helices H6, H7, and H50, while the central pore is located below the ribosome tunnel exit. Hence, this copy of Sec61 is positioned to capture and translocate the nascent chain. Finally, we show that mammalian and bacterial ribosome-channel complexes have similar architectures.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Ribossomos
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Proteínas de Ligação ao Cálcio
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Glicoproteínas de Membrana
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Receptores de Peptídeos
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Receptores Citoplasmáticos e Nucleares
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Proteínas de Membrana
Tipo de estudo:
Risk_factors_studies
Limite:
Animals
Idioma:
En
Revista:
Structure
Assunto da revista:
BIOLOGIA MOLECULAR
/
BIOQUIMICA
/
BIOTECNOLOGIA
Ano de publicação:
2008
Tipo de documento:
Article
País de afiliação:
Estados Unidos
País de publicação:
EEUU
/
ESTADOS UNIDOS
/
ESTADOS UNIDOS DA AMERICA
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EUA
/
UNITED STATES
/
UNITED STATES OF AMERICA
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US
/
USA