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Published February 18, 2011 | Supplemental Material + Accepted Version
Journal Article Open

The Crystal Structure of the Signal Recognition Particle in Complex with Its Receptor


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.

Additional Information

© 2011 American Association for the Advancement of Science. Received for publication 13 August 2010. Accepted for publication 18 January 2011. We thank K. Zhou for excellent technical assistance and help with crystal preparation during the early stages of the project. Initial crystallographic analysis was performed at beamline 8.2.2 at the Advanced Light Source (ALS), Lawrence Berkeley National Laboratory; we acknowledge C. Ralston for outstanding technical assistance at the ALS. Crystallographic data were collected at the beamline X06SA at the Swiss Light Source (SLS). We thank A. Brunger for the prerelease version of CNS and for helpful comments on the refinement, C. Schulze-Briese and T. Tomizaki for their outstanding support at the SLS, T. Maier and S. Klinge for critical discussion and reading of the manuscript, and T. Maier and M. Leibundgut for help and assistance with data collection and solving the structure. S.F.A. was funded initially by the Howard Hughes Medical Institute and currently by an ETH postdoctoral fellowship, N.S. is funded by Boehringer Ingelheim Fonds, and K.S. is funded by NIH grant GM078024 to S.S. This work was supported in part by the Howard Hughes Medical Institute (J.A.D.) and by the Swiss National Science Foundation (SNSF) and the National Center of Excellence in Research (NCCR) Structural Biology program of the SNSF. Atomic coordinates and structure factors for the SRP:SR crystal structure have been deposited with the Protein Data Bank under accession code 2xxa.

Attached Files

Accepted Version - nihms505518.pdf

Supplemental Material - Ataide.SOM.pdf


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