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Signal recognition particle mediates post-translational targeting in eukaryotes
Benjamin M Abell1, Martin R Pool, Oliver Schlenker
1School of Biological Sciences, University of Manchester, Manchester, UK.
The EMBO Journal
|July 2, 2004
Summary
Signal recognition particle (SRP) can now target tail-anchored (TA) proteins post-translationally to the endoplasmic reticulum (ER). This reveals a new SRP pathway for TA protein biogenesis.
Area of Science:
- Cell Biology
- Molecular Biology
- Protein Trafficking
Background:
- Signal recognition particle (SRP) mediates cotranslational delivery of proteins to the ER.
- Eukaryotic SRP function has been primarily understood as a cotranslational process.
- Tail-anchored (TA) proteins have unique C-terminal membrane insertion signals.
Purpose of the Study:
- To investigate a potential post-translational role for SRP in protein targeting.
- To elucidate the mechanism of endoplasmic reticulum (ER) targeting for tail-anchored (TA) proteins.
- To determine if SRP can mediate post-translational targeting of TA proteins to the ER.
Main Methods:
- Investigated SRP interaction with newly synthesized TA proteins.
- Utilized GTP dependency and SRP receptor assays.
- Analyzed precursor specificity in SRP-dependent targeting pathways.
Main Results:
- Demonstrated that SRP can associate post-translationally with TA protein targeting signals.
- Showed SRP delivers TA proteins to the ER membrane via a GTP- and SRP receptor-dependent pathway.
- Identified precursor specificity in the requirement for this SRP-dependent route.
Conclusions:
- SRP exhibits a novel post-translational function in targeting TA proteins to the ER.
- A new pathway for TA protein biogenesis involving post-translational SRP action is proposed.
- This finding expands the known mechanisms of SRP-mediated protein targeting.