Signal recognition particle

__NOTOC__protein
Name = signal recognition particle 9kDa
caption =


width =
HGNCid = 11304
Symbol = SRP9
AltSymbols =
EntrezGene = 6726
OMIM = 600707
RefSeq = NM_003133
UniProt = P49458
PDB =
ECnumber =
Chromosome = 1
Arm = q
Band = 42.12
LocusSupplementaryData = protein
Name = signal recognition particle 14kDa
caption =


width =
HGNCid = 11299
Symbol = SRP14
AltSymbols =
EntrezGene = 6727
OMIM = 600708
RefSeq = NM_003134
UniProt = P37108
PDB =
ECnumber =
Chromosome = 15
Arm = q
Band = 22
LocusSupplementaryData = protein
Name = signal recognition particle 19kDa
caption =


width =
HGNCid = 11300
Symbol = SRP19
AltSymbols =
EntrezGene = 6728
OMIM = 182175
RefSeq = NM_003135
UniProt = P09132
PDB =
ECnumber =
Chromosome = 5
Arm = q
Band = 21
LocusSupplementaryData = -q22protein
Name = signal recognition particle 54kDa
caption =


width =
HGNCid = 11301
Symbol = SRP54
AltSymbols =
EntrezGene = 6729
OMIM = 604857
RefSeq = NM_003136
UniProt = P61011
PDB =
ECnumber =
Chromosome = 14
Arm = q
Band = 13.2
LocusSupplementaryData = protein
Name = signal recognition particle 68kDa
caption =


width =
HGNCid = 11302
Symbol = SRP68
AltSymbols =
EntrezGene = 6730
OMIM = 604858
RefSeq = NM_014230
UniProt = Q9UHB9
PDB =
ECnumber =
Chromosome = 17
Arm = q
Band = 25.1
LocusSupplementaryData = protein
Name = signal recognition particle 72kDa
caption =


width =
HGNCid = 11303
Symbol = SRP72
AltSymbols =
EntrezGene = 6731
OMIM = 602122
RefSeq = NM_006947
UniProt = O76094
PDB =
ECnumber =
Chromosome = 4
Arm = q
Band = 11
LocusSupplementaryData = 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. [ [http://www.ncbi.nlm.nih.gov/books/bv.fcgi?highlight=mboc4,Signal%20Recognition%20Particle&rid=mboc4.section.2202#2213 MBOC4 at NCB] ] 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.

tructure

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.cite journal | author = Leslie M | title = Isolating SRP | journal = The Journal of Cell Biology | volume = 171 | issue = 1 | pages = 13-14 | year = | month = | pmid = | doi = 10.1083/jcb1711fta2 | url = | issn = ]

References

External links

*
* [http://rnp.uthct.edu/ Signal Recognition Particle Database]
* [http://nobelprize.org/nobel_prizes/medicine/laureates/1999/index.html 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