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Signal recognition particle Overview

GO Annotations consist of four mandatory components: a gene product, a term from one of the three Gene Ontology (GO) controlled vocabularies (Molecular Function, Biological Process, and Cellular Component), a reference, and an evidence code.


Summary
A conserved ribonucleoprotein particle, which includes in its structure a small cytoplasmic RNA (scRNA). In co-translational targeting of membrane and secretory proteins, SRP recognizes signal sequences as soon as they emerge from the ribosomal polypeptide exit tunnel and binds to the ribosome-nascent chain complex (RNC), leading to retardation of peptide elongation. The SRP-RNC complex is targeted to the endoplasmic reticulum (ER) membrane by interaction with the SRP receptor (SR). After docking to the membrane, the RNC is transferred to the protein-conducting channel, the translocon, and protein synthesis continues. The SRP-SR complex dissociates from the ribosome and, as a result of GTP hydrolysis, SRP and SR dissociate from each other. GTP binding to both SRP and SR is required for SRP-SR complex formation. Signal sequence binding and GTP-dependent interaction with SR are mediated by the SRP54 subunit, a multidomain protein with an N-terminal four-helix bundle (N domain), a central GTPase domain (G domain) and a C-terminal methionine-rich domain (M domain). The N-terminal domain (SRP54N) is tightly associated with the G domain (SRP54NG) and may be involved in regulating GTP affinity. The genes encoding scR1 and SRP54p are not essential for growth, although SRP-deficient cells grow poorly, suggesting that an alternative, SRP-independent targeting pathway(s) to the ER membrane exists.
GO Slim Terms

The yeast GO Slim terms are higher level terms that best represent the major S. cerevisiae biological processes, functions, and cellular components. The GO Slim terms listed here are the broader parent terms for the specific terms to which this gene product is annotated, and thus represent the more general processes, functions, and components in which it is involved.

GTPase activity, hydrolase activity, cellular component assembly, protein-containing complex assembly, ribonucleoprotein complex, signal recognition particle, endoplasmic reticulum targeting