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An interaction between the SRP receptor and the translocon is critical during cotranslational protein translocation
The signal recognition particle (SRP)–dependent targeting pathway facilitates rapid, efficient delivery of the ribosome–nascent chain complex (RNC) to the protein translocation channel. We test whether the SRP receptor (SR) locates a vacant protein translocation channel by interacting with the yeast...
Autores principales: | , , , |
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Formato: | Texto |
Lenguaje: | English |
Publicado: |
The Rockefeller University Press
2008
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2290843/ https://www.ncbi.nlm.nih.gov/pubmed/18347066 http://dx.doi.org/10.1083/jcb.200707196 |
Sumario: | The signal recognition particle (SRP)–dependent targeting pathway facilitates rapid, efficient delivery of the ribosome–nascent chain complex (RNC) to the protein translocation channel. We test whether the SRP receptor (SR) locates a vacant protein translocation channel by interacting with the yeast Sec61 and Ssh1 translocons. Surprisingly, the slow growth and cotranslational translocation defects caused by deletion of the transmembrane (TM) span of yeast SRβ (SRβ-ΔTM) are exaggerated when the SSH1 gene is disrupted. Disruption of the SBH2 gene, which encodes the β subunit of the Ssh1p complex, likewise causes a growth defect when combined with SRβ-ΔTM. Cotranslational translocation defects in the ssh1ΔSRβ-ΔTM mutant are explained by slow and inefficient in vivo gating of translocons by RNCs. A critical function for translocation channel β subunits in the SR–channel interaction is supported by the observation that simultaneous deletion of Sbh1p and Sbh2p causes a defect in the cotranslational targeting pathway that is similar to the translocation defect caused by deletion of either subunit of the SR. |
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