The crystal structure of the signal recognition particle in complex with its receptor |
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Authors: | Ataide Sandro F Schmitz Nikolaus Shen Kuang Ke Ailong Shan Shu-ou Doudna Jennifer A Ban Nenad |
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Affiliation: | Institute of Molecular Biology and Biophysics, Eidgen?ssische Technische Hochschule Zurich (ETH Zurich), Zurich, Switzerland. |
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Abstract: | Cotranslational targeting of membrane and secretory proteins is mediated by the universally conserved signal recognition particle (SRP). Together with its receptor (SR), SRP mediates the guanine triphosphate (GTP)-dependent delivery of translating ribosomes bearing signal sequences to translocons on the target membrane. Here, we present the crystal structure of the SRP:SR complex at 3.9 angstrom resolution and biochemical data revealing that the activated SRP:SR guanine triphosphatase (GTPase) complex binds the distal end of the SRP hairpin RNA where GTP hydrolysis is stimulated. Combined with previous findings, these results suggest that the SRP:SR GTPase complex initially assembles at the tetraloop end of the SRP RNA and then relocalizes to the opposite end of the RNA. This rearrangement provides a mechanism for coupling GTP hydrolysis to the handover of cargo to the translocon. |
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