Seroatlas · Human Serome Atlas

TMEM203

Transmembrane protein 203

Also known as: HBEBP1, MGC14327, TM203_HUMAN

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

Protein identityUniProt · HPA

UniProt accession: Q969S6
Gene: TMEM203
Ensembl: ENSG00000187713
Chromosome: 9
Canonical length: 136 aa
Protein class: Predicted membrane proteins, Transporters
Quaternary structure: Homodimer

OverviewNCBI Gene

Involved in intracellular calcium ion homeostasis. Located in endoplasmic reticulum. [provided by Alliance of Genome Resources, Jul 2025]

Canonical amino-acid sequenceUniProt

136 residues, UniProt reviewed canonical sequence.

>Q969S6|TMEM203
     1  MLFSLRELVQ WLGFATFEIF VHLLALLVFS VLLALRVDGL VPGLSWWNVF VPFFAADGLS
    61  TYFTTIVSVR LFQDGEKRLA VLRLFWVLTV LSLKFVFEML LCQKLAEQTR ELWFGLITSP
   121  LFILLQLLMI RACRVN

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against TMEM203 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: 4
Mean surface accessibility (rSASA): 0.35
Highest tissue expression: 47 nTPM

Expression across tissuesHPA

Tissue

skeletal muscle: 47 nTPM
liver: 47 nTPM
heart muscle: 43 nTPM
tongue: 43 nTPM
skin: 41 nTPM
choroid plexus: 36 nTPM

Single-cell type

esophageal suprabasal cells: 52 nCPM
esophageal basal cells: 47 nCPM
cholangiocytes: 46 nCPM
breast myoepithelial cells: 46 nCPM
esophageal apical cells: 45 nCPM
hepatocytes: 44 nCPM

Immune cell

naive CD4 T-cell: 8.7 nTPM
memory B-cell: 8.3 nTPM
NK-cell: 7.5 nTPM
memory CD8 T-cell: 6.5 nTPM
MAIT T-cell: 6.4 nTPM
naive CD8 T-cell: 6.1 nTPM

Brain region

thalamus: 33 nTPM
midbrain: 30 nTPM
cerebellum: 30 nTPM
medulla oblongata: 30 nTPM
hypothalamus: 29 nTPM
basal ganglia: 29 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): 0.92
gnomAD pLI: 0.63
gnomAD missense Z: 1.81
DepMap mean gene effect: 0.15
DepMap dependency class: none

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

Transmembrane Fragile-X-F-associated protein

KeywordsUniProt

InteractionsUniProt · HPA

Protein binding partners of TMEM203 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 TMEM203 as an antibody target. Whether an autoantibody or antibody against TMEM203 could matter depends on whether native TMEM203 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

TMEM203 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 TMEM203 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

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