Seroatlas · Human Serome Atlas

SPACA3

Sperm acrosome membrane-associated protein 3

Also known as: ALLP17, CT54, LYC3, LYZL3, SACA3_HUMAN, SLLP1

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

Protein identityUniProt · HPA

UniProt accession: Q8IXA5
Gene: SPACA3
Ensembl: ENSG00000141316
Chromosome: 17
Canonical length: 215 aa
Protein class: Predicted intracellular proteins, Predicted membrane proteins, Predicted secreted proteins
Subcellular location: Acrosome
Secretome location: Secreted in male reproductive system

OverviewNCBI Gene

The protein encoded by this gene is a sperm surface protein that may be involved in adhesion to the egg prior to fertilization. While the encoded protein has significant similarity to lysozyme at the amino acid level, it has no detectable bacteriocidal activity. Several transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Nov 2015]

Canonical amino-acid sequenceUniProt

215 residues, UniProt reviewed canonical sequence.

>Q8IXA5|SPACA3
     1  MVSALRGAPL IRVHSSPVSS PSVSGPRRLV SCLSSQSSAL SQSGGGSTSA AGIEARSRAL
    61  RRRWCPAGIM LLALVCLLSC LLPSSEAKLY GRCELARVLH DFGLDGYRGY SLADWVCLAY
   121  FTSGFNAAAL DYEADGSTNN GIFQINSRRW CSNLTPNVPN VCRMYCSDLL NPNLKDTVIC
   181  AMKITQEPQG LGYWEAWRHH CQGKDLTEWV DGCDF

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against SPACA3 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: Secreted
Secreted: Yes
Transmembrane segments: 1
Mean surface accessibility (rSASA): 0.44
Highest tissue expression: 118 nTPM

Expression across tissuesHPA

Tissue

testis: 118 nTPM
pancreas: 20 nTPM
choroid plexus: 1.7 nTPM
bone marrow: 0.3 nTPM
small intestine: 0.3 nTPM
epididymis: 0.2 nTPM

Single-cell type

early spermatids: 1,521 nCPM
late spermatids: 1,393 nCPM
late primary spermatocytes: 614 nCPM
pancreatic acinar cells: 21 nCPM
sertoli cells: 8.6 nCPM
leydig cells: 5.2 nCPM

Immune cell

memory B-cell: 1.2 nTPM
plasmacytoid DC: 0.2 nTPM
basophil: 0 nTPM
classical monocyte: 0 nTPM
eosinophil: 0 nTPM
gdT-cell: 0 nTPM

Brain region

cerebellum: 2.9 nTPM
amygdala: 1.9 nTPM
cerebral cortex: 1.9 nTPM
hippocampal formation: 1.8 nTPM
pons: 1.8 nTPM
choroid plexus: 1.7 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): 1.39
gnomAD pLI: 0
gnomAD missense Z: -0.38
DepMap mean gene effect: 0.01
DepMap dependency class: selective

Cancer expressionTCGA

Across TCGA tumor cohorts, this protein is over-expressed in roughly 3% 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

InteractionsUniProt · HPA

Protein binding partners of SPACA3 in the human serome: UniProt-annotated complex subunits plus reported interactors. Each links to its own Seroatlas record.

ASTL

Antibody and autoantibody relevanceSeroatlas analysis

Seroatlas reads SPACA3 as an antibody target. Whether an autoantibody or antibody against SPACA3 could matter depends on whether native SPACA3 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

SPACA3 is annotated as secreted, so native SPACA3 circulates and is directly accessible to antibodies. Secreted and cell-surface proteins are the autoantibody targets most likely to act like drugs, blocking or depleting the native protein.

Annotation status

The present source text does not explicitly label SPACA3 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

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