Seroatlas · Human Serome Atlas

SSR1

Translocon-associated protein subunit alpha

Also known as: SSRA_HUMAN, TRAPA

Cross-references: UniProt · Ensembl · Human Protein Atlas · GeneCards · NCBI Gene

Protein identityUniProt · HPA

UniProt accession
P43307
Gene
SSR1
Ensembl
ENSG00000124783
Chromosome
6
Canonical length
286 aa
Protein class
Predicted membrane proteins, Transporters
Subcellular location
Endoplasmic reticulum

OverviewNCBI Gene

The signal sequence receptor (SSR) is a glycosylated endoplasmic reticulum (ER) membrane receptor associated with protein translocation across the ER membrane. The SSR consists of 2 subunits, a 34-kD glycoprotein encoded by this gene and a 22-kD glycoprotein. This gene generates several mRNA species as a result of complex alternative polyadenylation. This gene is unusual in that it utilizes arrays of polyA signal sequences that are mostly non-canonical. Multiple transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, May 2014]

Canonical amino-acid sequenceUniProt

286 residues, UniProt reviewed canonical sequence.

>P43307|SSR1
     1  MRLLPRLLLL LLLVFPATVL FRGGPRGLLA VAQDLTEDEE TVEDSIIEDE DDEAEVEEDE
    61  PTDLVEDKEE EDVSGEPEAS PSADTTILFV KGEDFPANNI VKFLVGFTNK GTEDFIVESL
   121  DASFRYPQDY QFYIQNFTAL PLNTVVPPQR QATFEYSFIP AEPMGGRPFG LVINLNYKDL
   181  NGNVFQDAVF NQTVTVIERE DGLDGETIFM YMFLAGLGLL VIVGLHQLLE SRKRKRPIQK
   241  VEMGTSSQND VDMSWIPQET LNQINKASPR RLPRKRAQKR SVGSDE

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against SSR1 can act on the native protein depends on physical access: surface and secreted proteins are reachable by circulating antibodies, intracellular proteins usually are not.

Antibody reachability
Other membrane
Secreted
No
Transmembrane segments
1
Mean surface accessibility (rSASA)
0.49
Highest tissue expression
96 nTPM

Expression across tissuesHPA

Tissue

  • bone marrow: 96 nTPM
  • liver: 89 nTPM
  • appendix: 84 nTPM
  • cervix: 83 nTPM
  • thyroid gland: 79 nTPM
  • tonsil: 79 nTPM

Single-cell type

  • extravillous trophoblasts: 279 nCPM
  • plasma cells: 277 nCPM
  • esophageal suprabasal cells: 218 nCPM
  • parietal cells: 209 nCPM
  • kupffer cells: 197 nCPM
  • gastric progenitor cells: 196 nCPM

Immune cell

  • total PBMC: 215 nTPM
  • myeloid DC: 200 nTPM
  • classical monocyte: 170 nTPM
  • basophil: 146 nTPM
  • plasmacytoid DC: 140 nTPM
  • intermediate monocyte: 122 nTPM

Brain region

  • choroid plexus: 89 nTPM
  • white matter: 83 nTPM
  • hypothalamus: 75 nTPM
  • thalamus: 74 nTPM
  • medulla oblongata: 74 nTPM
  • midbrain: 67 nTPM

Genetic constraint and essentialitygnomAD · DepMap

Does the body need this protein intact? Low LOEUF or a strong DepMap dependency means loss or blockade of the protein is likely to be felt.

gnomAD LOEUF (loss-of-function intolerance)
0.55
gnomAD pLI
0.27
gnomAD missense Z
1.45
DepMap mean gene effect
0
DepMap dependency class
selective

Cancer expressionTCGA

Across TCGA tumor cohorts, this protein is over-expressed in roughly 6% of surveyed tumor types (aggregate summary; per-cohort expression, alteration, and survival load in the interactive view).

OntologyGO

Biological processes

Cellular components

Protein domainsUniProt · Pfam · InterPro

  • Translocon-associated protein (TRAP), alpha subunit
  • Translocon-associated protein (TRAP), alpha subunit

KeywordsUniProt

InteractionsUniProt · HPA

Protein binding partners of SSR1 in the human serome: UniProt-annotated complex subunits plus reported interactors. Each links to its own Seroatlas record.

Antibody and autoantibody relevanceSeroatlas analysis

Seroatlas reads SSR1 as an antibody target. Whether an autoantibody or antibody against SSR1 could matter depends on whether native SSR1 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

SSR1 is annotated as predominantly intracellular. Intracellular proteins are common autoantibody markers, becoming visible to the immune system after cell injury or altered processing, but are usually markers of disease rather than direct drivers.

Annotation status

The present source text does not explicitly label SSR1 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

Canonical record: https://seroatlas.com/gene/SSR1. Study-independent annotations aggregated from UniProt, Human Protein Atlas, PubMed, IEDB, Pfam, InterPro, Gene Ontology, AlphaFold, gnomAD, DepMap, ClinVar, TCGA. Catalog release seroatlas-reviewed-human-uniprot-20260313.

Seroatlas is the reference for exploring autoantibody and antibody serology at the human-protein level: the autoreactome and human serome, multiplex serology (HuProt, HuScan, VirScan, PhIP-Seq).

© 2026 · Seroatlas, Discover Oregon LLC · Terms of use

Loading the interactive Seroatlas protein explorer...