SRP68/YPL243W Summary Help

Standard Name SRP68
Systematic Name YPL243W
Feature Type ORF, Verified
Description Core component of the signal recognition particle (SRP) complex; SRP complex functions in targeting nascent secretory proteins to the endoplasmic reticulum (ER) membrane; relocalizes from cytoplasm to the nuclear periphery upon DNA replication stress (1, 2, 3 and see Summary Paragraph)
Name Description Signal Recognition Particle
Chromosomal Location
ChrXVI:88517 to 90316 | ORF Map | GBrowse
Gene Ontology Annotations All SRP68 GO evidence and references
  View Computational GO annotations for SRP68
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Regulators 2 genes
Classical genetics
Large-scale survey
reduction of function
42 total interaction(s) for 23 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 32
  • Affinity Capture-RNA: 3
  • Affinity Capture-Western: 2
  • Co-purification: 2
  • Two-hybrid: 1

Genetic Interactions
  • Synthetic Growth Defect: 2

Expression Summary
Length (a.a.) 599
Molecular Weight (Da) 69,005
Isoelectric Point (pI) 9.44
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrXVI:88517 to 90316 | ORF Map | GBrowse
Last Update Coordinates: 1996-07-31 | Sequence: 1996-07-31
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..1800 88517..90316 1996-07-31 1996-07-31
Retrieve sequences
Analyze Sequence
S288C only
S288C vs. other species
S288C vs. other strains
External Links All Associated Seq | Entrez Gene | Entrez RefSeq Protein | MIPS | Search all NCBI (Entrez) | UniProtKB
Primary SGDIDS000006164

The signal recognition particle (SRP) is an abundant and conserved ribonucleoprotein necessary for targeting proteins to the endoplasmic reticulum membrane (4). SRP in eukaryotes contains six subunits and a 7S RNA molecule; in S. cerevisiae the subunits are encoded by SRP14, SRP21, SRP68, SRP72, SEC65, and SRP54, and the RNA (termed scR1) is encoded by SCR1 (4, 1). With the exception of Srp54p, the proteins and RNA assemble into a core complex in the nucleus; this particle is exported to the cytoplasm where Srp54p joins to form the complete complex (5). Sec65p is required for association of Srp54p with the SRP particle (6). Loss of any of the SRP components causes a slow growth phenotype and loss of SRP-mediated translocation, but not cell death, indicating that the signal recognition particle is not essential in yeast and SRP-independent translocation can occur (4, 1).

The first step of SRP-mediated cotranslational targeting is interaction between SRP and the ribosome nascent chain complex (RNC), which is comprised of the translating ribosome and the emerging nascent protein. SRP interacts with the RNC through the N-terminal hydrophobic signal sequence of the nascent protein. SRP then directs the RNC to the ER membrane via interaction between SRP and a signal receptor complex (SR), encoded by SRP101 and SRP102. Finally, the RNC is transferred to the translocon, a protein-conducting membrane channel, and SRP and the SR dissociate. GTP binding by both SRP (via the Srp54p subunit) and the SR is critical for their interaction, and GTP hydrolysis facilitates their dissociation (reviewed in 7, and see 7 for more details).

Last updated: 2008-08-11 Contact SGD

References cited on this page View Complete Literature Guide for SRP68
1) Brown JD, et al.  (1994) Subunits of the Saccharomyces cerevisiae signal recognition particle required for its functional expression. EMBO J 13(18):4390-400
2) Grosshans H, et al.  (2001) Biogenesis of the signal recognition particle (SRP) involves import of SRP proteins into the nucleolus, assembly with the SRP-RNA, and Xpo1p-mediated export. J Cell Biol 153(4):745-62
3) Tkach JM, et al.  (2012) Dissecting DNA damage response pathways by analysing protein localization and abundance changes during DNA replication stress. Nat Cell Biol 14(9):966-76
4) Hann BC and Walter P  (1991) The signal recognition particle in S. cerevisiae. Cell 67(1):131-44
5) Ciufo LF and Brown JD  (2000) Nuclear export of yeast signal recognition particle lacking Srp54p by the Xpo1p/Crm1p NES-dependent pathway. Curr Biol 10(20):1256-64
6) Stirling CJ and Hewitt EW  (1992) The S. cerevisiae SEC65 gene encodes a component of yeast signal recognition particle with homology to human SRP19. Nature 356(6369):534-7
7) Wild K, et al.  (2004) SRP meets the ribosome. Nat Struct Mol Biol 11(11):1049-53