Seroatlas · Human Serome Atlas

SPAG6

Sperm-associated antigen 6

Also known as: CFAP194, CT141, FAP194, PF16, Repro-SA-1, SPAG6_HUMAN

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

Protein identityUniProt · HPA

UniProt accession
O75602
Gene
SPAG6
Ensembl
ENSG00000077327
Chromosome
10
Canonical length
509 aa
Protein class
Predicted intracellular proteins
Subcellular location
Calyx,Mid piece,Principal piece,End piece

OverviewNCBI Gene

The correlation of anti-sperm antibodies with cases of unexplained infertility implicates a role for these antibodies in blocking fertilization. Improved diagnosis and treatment of immunologic infertility, as well as identification of proteins for targeted contraception, are dependent on the identification and characterization of relevant sperm antigens. The protein expressed by this gene is recognized by anti-sperm antibodies from an infertile man. This protein localizes to the tail of permeabilized human sperm and contains eight contiguous armadillo repeats, a motif known to mediate protein-protein interactions. Studies in mice suggest that this protein is involved in sperm flagellar motility and maintenance of the structural integrity of mature sperm. Several transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Dec 2011]

Canonical amino-acid sequenceUniProt

509 residues, UniProt reviewed canonical sequence.

>O75602|SPAG6
     1  MSQRQVLQVF EQYQKARTQF VQMVAELATR PQNIETLQNA GVMSLLRTLL LDVVPTIQQT
    61  AALALGRLAN YNDDLAEAVV KCDILPQLVY SLAEQNRFYK KAAAFVLRAV GKHSPQLAQA
   121  IVDCGALDTL VICLEDFDPG VKEAAAWALR YIARHNAELS QAVVDAGAVP LLVLCIQEPE
   181  IALKRIAASA LSDIAKHSPE LAQTVVDAGA VAHLAQMILN PDAKLKHQIL SALSQVSKHS
   241  VDLAEMVVEA EIFPVVLTCL KDKDEYVKKN ASTLIREIAK HTPELSQLVV NAGGVAAVID
   301  CIGSCKGNTR LPGIMMLGYV AAHSENLAMA VIISKGVPQL SVCLSEEPED HIKAAAAWAL
   361  GQIGRHTPEH ARAVAVTNTL PVLLSLYMST ESSEDLQVKS KKAIKNILQK CTYLPALEPF
   421  LYDAPPNILK HVVGQFSKVL PHDSKARRLF VTSGGLKKVQ EIKAEPGSLL QEYINSINSC
   481  YPEEIVRYYS PGYSDTLLQR VDSYQPLNN

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against SPAG6 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
Intracellular
Secreted
No
Transmembrane segments
0
Mean surface accessibility (rSASA)
0.24
Highest tissue expression
94 nTPM

Expression across tissuesHPA

Tissue

  • choroid plexus: 94 nTPM
  • testis: 90 nTPM
  • fallopian tube: 46 nTPM
  • pituitary gland: 14 nTPM
  • hypothalamus: 9.4 nTPM
  • hippocampal formation: 8.3 nTPM

Single-cell type

  • late primary spermatocytes: 801 nCPM
  • early primary spermatocytes: 430 nCPM
  • respiratory ciliated cells: 362 nCPM
  • ependymal cells: 335 nCPM
  • fallopian tube ciliated cells: 307 nCPM
  • epididymal efferent duct ciliated cells: 304 nCPM

Immune cell

  • eosinophil: 0.6 nTPM
  • neutrophil: 0.2 nTPM
  • plasmacytoid DC: 0.2 nTPM
  • T-reg: 0.1 nTPM
  • basophil: 0 nTPM
  • classical monocyte: 0 nTPM

Brain region

  • choroid plexus: 134 nTPM
  • medulla oblongata: 39 nTPM
  • spinal cord: 36 nTPM
  • midbrain: 35 nTPM
  • white matter: 21 nTPM
  • pons: 14 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)
1.22
gnomAD pLI
0
gnomAD missense Z
0.74
DepMap mean gene effect
0.02
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

Molecular functions

Cellular components

Protein domainsUniProt · Pfam · InterPro

KeywordsUniProt

InteractionsUniProt · HPA

Protein binding partners of SPAG6 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 SPAG6 as an antibody target. Whether an autoantibody or antibody against SPAG6 could matter depends on whether native SPAG6 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

SPAG6 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.

Source-annotated serology context

The source annotations explicitly mention antibody, autoantibody, autoantigen, or autoimmune context. This is biological context, not study-specific reactivity.

  • The correlation of anti-sperm antibodies with cases of unexplained infertility implicates a role for these antibodies in blocking fertilization.
  • The protein expressed by this gene is recognized by anti-sperm antibodies from an infertile man.

Canonical record: https://seroatlas.com/gene/SPAG6. 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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