Seroatlas · Human Serome Atlas

SPACA4

Sperm acrosome membrane-associated protein 4

Also known as: SACA4_HUMAN, SAMP14

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

Protein identityUniProt · HPA

UniProt accession
Q8TDM5
Gene
SPACA4
Ensembl
ENSG00000177202
Chromosome
19
Canonical length
124 aa
Protein class
Predicted intracellular proteins
Subcellular location
Acrosome

OverviewNCBI Gene

Involved in binding activity of sperm to zona pellucida. Located in inner acrosomal membrane and outer acrosomal membrane. [provided by Alliance of Genome Resources, Jul 2025]

Canonical amino-acid sequenceUniProt

124 residues, UniProt reviewed canonical sequence.

>Q8TDM5|SPACA4
     1  MVLCWLLLLV MALPPGTTGV KDCVFCELTD SMQCPGTYMH CGDDEDCFTG HGVAPGTGPV
    61  INKGCLRATS CGLEEPVSYR GVTYSLTTNC CTGRLCNRAP SSQTVGATTS LALGLGMLLP
   121  PRLL

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against SPACA4 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
0
Mean surface accessibility (rSASA)
0.46
Highest tissue expression
112 nTPM

Expression across tissuesHPA

Tissue

  • testis: 112 nTPM
  • colon: 3.4 nTPM
  • stomach: 3.3 nTPM
  • small intestine: 2.9 nTPM
  • duodenum: 2.8 nTPM
  • salivary gland: 2.8 nTPM

Single-cell type

  • early spermatids: 1,274 nCPM
  • late primary spermatocytes: 405 nCPM
  • late spermatids: 210 nCPM
  • sertoli cells: 4.2 nCPM
  • peritubular myoid cells: 3.5 nCPM
  • esophageal apical cells: 2.3 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: 0.7 nTPM
  • cerebellum: 0.3 nTPM
  • hippocampal formation: 0.2 nTPM
  • medulla oblongata: 0.2 nTPM
  • pons: 0.2 nTPM
  • white matter: 0.2 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)
1.9
gnomAD pLI
0.28
gnomAD missense Z
0.91
DepMap mean gene effect
-0.03
DepMap dependency class
selective

Cancer expressionTCGA

Across TCGA tumor cohorts, this protein is over-expressed in roughly 4% 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

KeywordsUniProt

Antibody and autoantibody relevanceSeroatlas analysis

Seroatlas reads SPACA4 as an antibody target. Whether an autoantibody or antibody against SPACA4 could matter depends on whether native SPACA4 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

SPACA4 is annotated at the cell surface, where native SPACA4 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 SPACA4 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

Canonical record: https://seroatlas.com/gene/SPACA4. 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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