Summary: Signal recognition particle 9 kDa protein (SRP9)
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Signal recognition particle 9 kDa protein (SRP9) Provide feedback
This family consists of several eukaryotic SRP9 proteins. SRP9 together with the Alu-homologous region of 7SL RNA and SRP14 comprise the "Alu domain" of SRP, which mediates pausing of synthesis of ribosome associated nascent polypeptides that have been engaged by the targeting domain of SRP . This family also contains the homologous fungal SRP21 .
Hsu K, Chang DY, Maraia RJ; , J Biol Chem 1995;270:10179-10186.: Human signal recognition particle (SRP) Alu-associated protein also binds Alu interspersed repeat sequence RNAs. Characterization of human SRP9. PUBMED:7730321 EPMC:7730321
Brown JD, Hann BC, Medzihradszky KF, Niwa M, Burlingame AL, Walter P; , EMBO J. 1994;13:4390-4400.: Subunits of the Saccharomyces cerevisiae signal recognition particle required for its functional expression. PUBMED:7925282 EPMC:7925282
External database links
This tab holds annotation information from the InterPro database.
InterPro entry IPR008832
The signal recognition particle (SRP) is a multimeric protein, which along with its conjugate receptor (SR), is involved in targeting secretory proteins to the rough endoplasmic reticulum (RER) membrane in eukaryotes, or to the plasma membrane in prokaryotes [PUBMED:17622352, PUBMED:16469117]. SRP recognises the signal sequence of the nascent polypeptide on the ribosome, retards its elongation, and docks the SRP-ribosome-polypeptide complex to the RER membrane via the SR receptor. Eukaryotic SRP consists of six polypeptides (SRP9, SRP14, SRP19, SRP54, SRP68 and SRP72) and a single 300 nucleotide 7S RNA molecule. The RNA component catalyses the interaction of SRP with its SR receptor [PUBMED:17507650]. In higher eukaryotes, the SRP complex consists of the Alu domain and the S domain linked by the SRP RNA. The Alu domain consists of a heterodimer of SRP9 and SRP14 bound to the 5' and 3' terminal sequences of SRP RNA. This domain is necessary for retarding the elongation of the nascent polypeptide chain, which gives SRP time to dock the ribosome-polypeptide complex to the RER membrane. In archaea, the SRP complex contains 7S RNA like its eukaryotic counterpart, yet only includes two of the six protein subunits found in the eukarytic complex: SRP19 and SRP54 [PUBMED:12364595].
This entry represents the 9 kDa SRP9 component. Both SRP9 and SRP14 have the same (beta)-alpha-beta(3)-alpha fold. The heterodimer has pseudo two-fold symmetry and is saddle-like, consisting of a curved six-stranded beta-sheet that has four helices packed on the convex side and an exposed concave surface lined with positively charged residues. The SRP9/SRP14 heterodimer is essential for SRP RNA binding, mediating the pausing of synthesis of ribosome associated nascent polypeptides that have been engaged by the targeting domain of SRP [PUBMED:7730321].
The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.
|Cellular component||signal recognition particle (GO:0048500)|
|Molecular function||7S RNA binding (GO:0008312)|
|Biological process||SRP-dependent cotranslational protein targeting to membrane (GO:0006614)|
|negative regulation of translational elongation (GO:0045900)|
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|Seed source:||Pfam-B_7787 (release 8.0)|
|Number in seed:||33|
|Number in full:||286|
|Average length of the domain:||80.00 aa|
|Average identity of full alignment:||33 %|
|Average coverage of the sequence by the domain:||58.17 %|
|HMM build commands:||
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 23193494 -E 1000 --cpu 4 HMM pfamseq
|Family (HMM) version:||7|
|Download:||download the raw HMM for this family|
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For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the SRP9-21 domain has been found. There are 3 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein seqence.
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