Protein transport protein Sec61 subunit beta (SEC61B)
The protein contains 96 amino acids for an estimated molecular weight of 9974 Da.
Component of SEC61 channel-forming translocon complex that mediates transport of signal peptide-containing precursor polypeptides across the endoplasmic reticulum (ER) (PubMed:12475939). Component of a ribosome-associated ER translocon complex involved in multi-pass membrane protein transport into the ER membrane and biogenesis (PubMed:32820719). The SEC61 channel cooperates with the translocating protein TRAM1 to import nascent proteins into the ER (PubMed:19121997). Required for PKD1/Polycystin-1 biogenesis (By similarity). (updated: June 2, 2021)
Protein identification was indicated in the following studies:
- Bryk and co-workers. (2017) Quantitative Analysis of Human Red Blood Cell Proteome. J Proteome Res. 16(8), 2752-2761.
- D'Alessandro and co-workers. (2017) Red blood cell proteomics update: is there more to discover? Blood Transfus. 15(2), 182-187.
Methods
The following articles were analysed to gather the proteome content of erythrocytes.
The gene or protein list provided in the studies were processed using the ID mapping API of Uniprot in September 2018. The number of proteins identified and mapped without ambiguity in these studies is indicated below.
Only Swiss-Prot entries (reviewed) were considered for protein evidence assignation.
| Publication | Identification 1 | Uniprot mapping 2 | Not mapped / Obsolete | TrEMBL | Swiss-Prot |
|---|---|---|---|---|---|
| Goodman (2013) | 2289 (gene list) | 2278 | 53 | 20599 | 2269 |
| Lange (2014) | 1234 | 1234 | 7 | 28 | 1224 |
| Hegedus (2015) | 2638 | 2622 | 0 | 235 | 2387 |
| Wilson (2016) | 1658 | 1528 | 170 | 291 | 1068 |
| d'Alessandro (2017) | 1826 | 1817 | 2 | 0 | 1815 |
| Bryk (2017) | 2090 | 2060 | 10 | 108 | 1942 |
| Chu (2018) | 1853 | 1804 | 55 | 362 | 1387 |
1 as available in the article and/or in supplementary material
2 uniprot mapping returns all protein isoforms as one entry
The compilation of older studies can be retrieved from the Red Blood Cell Collection database.
The data and differentiation stages presented below come from the proteomic study and analysis performed by our partners of the GReX consortium, more details are available in their published work.
This protein is predicted to be membranous by TOPCONS.
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Biological Process
Posttranslational protein targeting to membrane, translocation
Protein insertion into ER membrane
Retrograde protein transport, ER to cytosol
SRP-dependent cotranslational protein targeting to membrane, translocation
Ubiquitin-dependent ERAD pathway
The reference OMIM entry for this protein is 609214
Sec61 complex, beta subunit; sec61b
DESCRIPTION
SEC61B is a subunit of the heteromeric SEC61 complex, which also contains alpha (SEC61A1; 609213) and gamma (SEC61G; 609215) subunits. The SEC61 complex forms the core of the mammalian endoplasmic reticulum (ER) translocon, a transmembrane channel for the translocation of proteins across the ER membrane (Greenfield and High, 1999).CLONING
Hartmann et al. (1994) purified the Sec61 complex from canine pancreatic microsomes. Using degenerate oligonucleotides based on the peptide sequences to probe a HeLa cell cDNA library, they cloned human SEC61B. The deduced 96-amino acid protein has a calculated molecular mass of about 10 kD.GENE FUNCTION
The SEC61 complex is an essential translocation component that can associate with either ribosomes or the SEC62 (602173)/SEC63 (608648) complex to perform cotranslational or posttranslational transport, respectively (Wiertz et al., 1996). It was originally thought to have a role only in translocation of proteins from the cytosol into the ER. However, Wiertz et al. (1996), Bebok et al. (1998), Chen et al. (1998), and Petaja-Repo et al. (2001) presented evidence suggesting that the human SEC61 complex can also function in retrograde transport of multidomain integral membrane proteins from the ER to the cytosol for proteasomal degradation. Bebok et al. (1998) found that CFTR (602421) could be coimmunoprecipitated in a complex with SEC61B in the cytosolic fraction of HeLa cells, suggesting that CFTR can be cut from the membrane in complex with SEC61B. They hypothesized that SEC61B escorts complex membrane proteins through the SEC61 complex in the retrograde direction for degradation by the proteasome or other proteolytic systems. By immunolocalization of fluorescence-tagged canine Sec61a transfected into COS-1 cells, Greenfield and High (1999) determined that the Sec61 complex distributed to both the ER and the ER-Golgi intermediate compartment, but not to the trans-Golgi network. Endogenous Sec61b and Sec61g showed the same distribution. Another translocon component, the glycoprotein Tram (see 605190) was also present in post-ER compartments, suggesting that the core components of the mammalian ER translocon are not permanently resident in the ER, but rather they are maintained in the ER by a specific retrieval mechanism. Sessions et al. (2009) identified insect host factors required for dengue virus (see 614371) propagation by carrying out a genomewide RNA interference screen in D. melanogaster cells using a well established 22,632 double-stranded RNA library. This screen identified 116 candidate dengue virus host factors (DVHFs). Although some were previously associated with flaviviruses, most of the DVHFs were newly implicated in dengue virus propagation. The dipteran DVHFs had 82 readily recognizable human homologs and, using a targeted short interfering RNA screen, they showed that 42 of these are human DVHFs. These include NPR2 (108961), SEC61B, TMEM214, TAZ (300394), EXDL2, and CNOT2 (604909). Sessions et al. (2009) concluded that this overlap indicates notable conservation of required factors between dipteran and human hosts.MAPPING
The International Radiation Hybrid Mapping Consortium mapped the SEC61B gene to chromosome 9 (TMAP SHGC-15224). ... More on the omim web site
July 1, 2021: Protein entry updated
Automatic update: Entry updated from uniprot information.
April 10, 2021: Protein entry updated
Automatic update: Entry updated from uniprot information.
June 30, 2020: Protein entry updated
Automatic update: OMIM entry 609214 was added.
Oct. 19, 2018: Additional information
Initial protein addition to the database. This entry was referenced in Bryk and co-workers. (2017).