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3.A.5.9.1
Sec-SRP translocase complex. The BAP29 and BAP31 (also called BCAP31) proteins interact directly with the Sec translocon (Wilson & Barlowe et al., 2010).  SRP68 and SRP72 form a complex with SRP RNA and SRP19.  The SRP68 binding site for the RNA is a tetratricopeptide-like module that bends the RNA and inserts an arginine-rich helix into the major groove to open the conserved 5f RNA loop and remodel the RNA for protein translocation (Grotwinkel et al. 2014).  Sec31 (Sec 31L1; HSPC334; HSPC275) is an outer cage component of the coat protein complex II (COPII) machinery which is recruited to specialized regions of the ER, called ER exit sites (ERES), where it plays a central role in the early secretory pathway. Sec31 also interacts with ALG-2 (Programed cell death protein 6 (PDCD6)) and annexin A11 (AnxA11) (Shibata et al. 2015). The Sec61 translocon mediates poorly efficient membrane insertion of Arg-containing TMSs, but a combination of arginine snorkeling, bilayer deformation, and peptide tilting is sufficient to lower the penalty of Arg insertion to an extent that a hydrophobic TMS with a central Arg residue readily inserts into a membrane (Ulmschneider et al. 2017). Mycolactone is a bacterium-derived macrolide that blocks the biogenesis of a large array of secretory and integral transmembrane proteins through potent inhibition of the Sec61 translocon (Morel et al. 2018). The Sec61α subunit possesses an opening between TMS2b and TMS7, the lateral gate, that is the exit for signal sequences and TMSs of translocating polypeptides to the lipid bilayer (Kida and Sakaguchi 2018). BCAP31 (BAP31; 246 aas and 3 N-terminal TMSs) is an ER chaparone that plays a role in the export of secreted proteins in the ER as well as the recognition of abnormally folded protein for targeting to the ER associated-degradation (ERAD) pathway (Wakana et al. 2008). It also serves as a cargo receptor for the export of transmembrane proteins (Annaert et al. 1997). Sec61 is the target of the cytotoxic plant-derived compound, ipomoeassin F (see TC family 8.C.10).

Accession Number:P37108
Protein Name:Signal recognition particle 14 kDa protein aka SRP14 aka 18 kDa ALU RNA binding protein
Length:136
Molecular Weight:14570.00
Species:Homo sapiens (Human) [9606]
Number of TMSs:1
Location1 / Topology2 / Orientation3: Cytoplasm1
Substrate protein polypeptide chain

Cross database links:

DIP: DIP-6152N
RefSeq: NP_003125.3   
Entrez Gene ID: 6727   
Pfam: PF02290   
OMIM: 600708  gene
KEGG: hsa:6727   

Gene Ontology

GO:0005786 C:signal recognition particle, endoplasmic re...
GO:0008312 F:7S RNA binding
GO:0030942 F:endoplasmic reticulum signal peptide binding
GO:0005515 F:protein binding
GO:0045900 P:negative regulation of translational elonga...
GO:0042493 P:response to drug
GO:0006614 P:SRP-dependent cotranslational protein targe...

References (5)

[1] “The SRP9/14 subunit of the signal recognition particle (SRP) is present in more than 20-fold excess over SRP in primate cells and exists primarily free but also in complex with small cytoplasmic Alu RNAs.”  Bovia F.et.al.   7542942
[2] “A human Alu RNA-binding protein whose expression is associated with accumulation of small cytoplasmic Alu RNA.”  Chang D.-Y.et.al.   8196634
[3] “Human protein factory for converting the transcriptome into an in vitro-expressed proteome.”  Goshima N.et.al.   19054851
[4] “Analysis of the DNA sequence and duplication history of human chromosome 15.”  Zody M.C.et.al.   16572171
[5] “The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC).”  The MGC Project Teamet.al.   15489334
Structure:
1E8O   1E8S   1RY1   4UYJ   4UYK   5AOX     

External Searches:

Analyze:

Predict TMSs (Predict number of transmembrane segments)
Window Size: Angle:  
FASTA formatted sequence
1:	MVLLESEQFL TELTRLFQKC RTSGSVYITL KKYDGRTKPI PKKGTVEGFE PADNKCLLRA 
61:	TDGKKKISTV VSSKEVNKFQ MAYSNLLRAN MDGLKKRDKK NKTKKTKAAA AAAAAAPAAA 
121:	ATAPTTAATT AATAAQ