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signal recognition particle 9kDa
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| Identifiers | |
| Symbol | SRP9 |
| Entrez | 6726 |
| HUGO | 11304 |
| OMIM | 600707 |
| RefSeq | NM_003133 |
| UniProt | P49458 |
| Other data | |
| Locus | Chr. 1 q42.12 |
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signal recognition particle 14kDa
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| Identifiers | |
| Symbol | SRP14 |
| Entrez | 6727 |
| HUGO | 11299 |
| OMIM | 600708 |
| RefSeq | NM_003134 |
| UniProt | P37108 |
| Other data | |
| Locus | Chr. 15 q22 |
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signal recognition particle 19kDa
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| Identifiers | |
| Symbol | SRP19 |
| Entrez | 6728 |
| HUGO | 11300 |
| OMIM | 182175 |
| RefSeq | NM_003135 |
| UniProt | P09132 |
| Other data | |
| Locus | Chr. 5 q21-q22 |
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signal recognition particle 54kDa
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| Identifiers | |
| Symbol | SRP54 |
| Entrez | 6729 |
| HUGO | 11301 |
| OMIM | 604857 |
| RefSeq | NM_003136 |
| UniProt | P61011 |
| Other data | |
| Locus | Chr. 14 q13.2 |
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signal recognition particle 68kDa
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| Identifiers | |
| Symbol | SRP68 |
| Entrez | 6730 |
| HUGO | 11302 |
| OMIM | 604858 |
| RefSeq | NM_014230 |
| UniProt | Q9UHB9 |
| Other data | |
| Locus | Chr. 17 q25.1 |
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signal recognition particle 72kDa
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| Identifiers | |
| Symbol | SRP72 |
| Entrez | 6731 |
| HUGO | 11303 |
| OMIM | 602122 |
| RefSeq | NM_006947 |
| UniProt | O76094 |
| Other data | |
| Locus | Chr. 4 q11 |
The signal recognition particle (SRP) is a ribonucleoprotein (protein-RNA complex) that recognizes and transports specific proteins to the endoplasmic reticulum in eukaryotes and the plasma membrane in prokaryotes.
Mechanism
The SRP is found in the cytosol. In eukaryotes, it binds to the endoplasmic reticulum signal sequence found in an emerging secretory protein and subsequently delivers the protein along with the ribosome to the membrane of the endoplasmic reticulum. When SRP binds the endoplasmic reticulum signal sequence, it also binds the ribosome and thereby pauses translation until the entire SRP-bound translation complex is transported to the endoplasmic reticulum, where translation resumes.
In the GTP-bound state, it recognizes an endoplasmic reticulum signal sequence of eight or more nonpolar amino acid residues at its center.1 It transiently binds to the endoplasmic reticulum signal sequence in a nascent protein, to the large ribosomal unit, and to the SRP receptor.
SRP and its receptor initiate the transfer of the nascent chain across the endoplasmic reticulum membrane. Once the chain reaches the translocon, SRP and its receptor both hydrolyze their bound GTP to GDP, then dislocate allowing translation to restart.
Structure
The core of the SRP is universal, being conserved in all three kingdoms. The eukaryotic SRP is composed of six distinct polypeptides bound to an RNA molecule (the 7SL RNA), with GTPase activity. The components of the complex are:
- P9
- P14
- P19
- P54
- P68
- P72
- SRP RNA
History
SRP was identified and characterized by Peter Walter when he was a graduate student in the laboratory of Günter Blobel.2
References
- ^ MBOC4 at NCB
- ^ Leslie M. "Isolating SRP". The Journal of Cell Biology 171 (1): 13-14. doi:.
External links
- MeSH Signal+Recognition+Particle
- Signal Recognition Particle Database
- The Nobel Prize in Physiology or Medicine 1999, "for the discovery that proteins have intrinsic signals that govern their transport and localization in the cell" to Günter Blobel, USA. Press Release, Illustrated Presentation, Presentation Speech
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Wikipedia content modification information:
- This page was last modified on 14 September 2008, at 01:43.
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