Seroatlas · Human Serome Atlas

SMIM9

Small integral membrane protein 9

Also known as: CXorf68, SMIM9_HUMAN

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

Protein identityUniProt · HPA

UniProt accession
A6NGZ8
Gene
SMIM9
Ensembl
ENSG00000203870
Chromosome
X
Canonical length
99 aa
Protein class
Predicted membrane proteins

OverviewNCBI Gene

Predicted to be located in plasma membrane. [provided by Alliance of Genome Resources, Jul 2025]

Canonical amino-acid sequenceUniProt

99 residues, UniProt reviewed canonical sequence.

>A6NGZ8|SMIM9
     1  MEPQKLLIIG FLLCSLTCLL LETVASSPLP LSALGIQEKT GSKPRSGGNH RSWLNNFRDY
    61  LWQLIKSALP PAAIVAFLLT SALMGILCCF TILVVDPVH

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against SMIM9 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
Cell surface
Secreted
No
Transmembrane segments
1
Mean surface accessibility (rSASA)
0.54
Highest tissue expression
0.6 nTPM

Expression across tissuesHPA

Tissue

  • testis: 0.6 nTPM
  • placenta: 0.1 nTPM
  • adipose tissue: 0 nTPM
  • adrenal gland: 0 nTPM
  • amygdala: 0 nTPM
  • appendix: 0 nTPM

Single-cell type

  • early spermatids: 28 nCPM
  • late primary spermatocytes: 25 nCPM
  • late spermatids: 13 nCPM
  • syncytiotrophoblasts: 3.8 nCPM
  • vascular endothelial cells: 2.2 nCPM
  • breast lactating cells: 1.1 nCPM

Immune cell

  • basophil: 0 nTPM
  • classical monocyte: 0 nTPM
  • eosinophil: 0 nTPM
  • gdT-cell: 0 nTPM
  • intermediate monocyte: 0 nTPM
  • MAIT T-cell: 0 nTPM

Brain region

  • cerebral cortex: 0.1 nTPM
  • pons: 0.1 nTPM
  • white matter: 0.1 nTPM
  • amygdala: 0 nTPM
  • basal ganglia: 0 nTPM
  • cerebellum: 0 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)
1.83
gnomAD pLI
0.01
gnomAD missense Z
0.36
DepMap mean gene effect
0.05
DepMap dependency class
none

OntologyGO

Cellular components

Protein domainsUniProt · Pfam · InterPro

  • Small integral membrane protein 9

KeywordsUniProt

Antibody and autoantibody relevanceSeroatlas analysis

Seroatlas reads SMIM9 as an antibody target. Whether an autoantibody or antibody against SMIM9 could matter depends on whether native SMIM9 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

SMIM9 is annotated at the cell surface, where native SMIM9 is exposed to circulating antibodies and is a prime autoantibody target that could block, deplete, or overstimulate it.

Annotation status

The present source text does not explicitly label SMIM9 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

Canonical record: https://seroatlas.com/gene/SMIM9. 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).

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