Translocon-associated protein subunit alpha (SSR1)
The protein contains 286 amino acids for an estimated molecular weight of 32235 Da.
TRAP proteins are part of a complex whose function is to bind calcium to the ER membrane and thereby regulate the retention of ER resident proteins. May be involved in the recycling of the translocation apparatus after completion of the translocation process or may function as a membrane-bound chaperone facilitating folding of translocated proteins. (updated: Oct. 10, 2018)
Protein identification was indicated in the following studies:
- Hegedűs and co-workers. (2015) Inconsistencies in the red blood cell membrane proteome analysis: generation of a database for research and diagnostic applications. Database (Oxford) 1-8.
- D'Alessandro and co-workers. (2017) Red blood cell proteomics update: is there more to discover? Blood Transfus. 15(2), 182-187.
- Bryk and co-workers. (2017) Quantitative Analysis of Human Red Blood Cell Proteome. J Proteome Res. 16(8), 2752-2761.
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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| Variant | Description |
|---|---|
| dbSNP:rs10004 |
Biological Process
Cotranslational protein targeting to membrane
IRE1-mediated unfolded protein response
Positive regulation of cell population proliferation
Cellular Component
Endoplasmic reticulum
Endoplasmic reticulum membrane
Integral component of membrane
Molecular Function
The reference OMIM entry for this protein is 600868
Signal sequence receptor, alpha; ssr1
DESCRIPTION
Transport of secretory and membrane proteins across the endoplasmic reticulum (ER) is thought to be mediated by a complex protein structure in the membrane called the translocon. SSR1 encodes the alpha subunit of the translocon-associated membrane protein (TRAP) complex and is found in close proximity of nascent polypeptide chains translocating across the ER membrane (summary by Hartmann and Prehn, 1994).CLONING
By screening a HeLa cell cDNA library using canine TRAP-alpha as probe, Hartmann and Prehn (1994) cloned human SSR1, which they called TRAP-alpha. The deduced 286-amino acid human protein contains an N-terminal signal sequence, followed by an acidic region, 2 glycosylation sites, a transmembrane domain, and 2 basic regions near the C terminus. Human and canine TRAP-alpha share 96% amino acid sequence identity. Hartmann and Prehn (1994) also identified TRAP-alpha sequences in trout, A. thaliana, and rice. Using RACE, Hirama et al. (1999) cloned full-length human TRAP-alpha, as well as several variants resulting from alternative polyadenylation. None of the predicted polyadenylation signals in the TRAP-alpha transcripts were canonical. The deduced full-length TRAP-alpha protein contains 286 amino acids. Northern blot analysis of the human myeloid and osteosarcoma cell lines detected a 3.3-kb TRAP-alpha transcript and several smaller transcripts.GENE FUNCTION
Using differential display, Hirama et al. (1999) found that TRAP-alpha was induced in a growth factor-dependent human myeloid cell line after stimulation with GMCSF (CSF2; 138960). Cell cycle analysis of human osteosarcoma cells showed that TRAP-alpha was downregulated in quiescent cells.MAPPING
Using radiation hybrid analysis, Hirama et al. (1999) mapped the SSR1 gene to chromosome 6p. Gross (2012) mapped the SSR1 gene to chromosome 6p24.3 based on an alignment of the SSR1 sequence (GenBank GENBANK AF156965) with the genomic sequence (GRCh37). ... More on the omim web site
July 5, 2019: Protein entry updated
Automatic update: OMIM entry 600868 was added.
Oct. 19, 2018: Additional information
Initial protein addition to the database. This entry was referenced in Bryk and co-workers. (2017).