Seroatlas · Human Serome Atlas

SPAG1

Sperm-associated antigen 1

Also known as: CILD28, CT140, DNAAF13, FLJ32920, HSD-3.8, SP75, SPAG1_HUMAN, TPIS

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

Protein identityUniProt · HPA

UniProt accession
Q07617
Gene
SPAG1
Ensembl
ENSG00000104450
Chromosome
8
Canonical length
926 aa
Protein class
Disease related genes, Human disease related genes, Predicted intracellular proteins
Subcellular location
Primary cilium,Cytosol,Principal 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 agglutinating antibodies from an infertile woman. Furthermore, immunization of female rats with the recombinant human protein reduced fertility. This protein localizes to the plasma membrane of germ cells in the testis and to the post-acrosomal plasma membrane of mature spermatozoa. Recombinant polypeptide binds GTP and exhibits GTPase activity. Thus, this protein may regulate GTP signal transduction pathways involved in spermatogenesis and fertilization. Two transcript variants of this gene encode the same protein. [provided by RefSeq, Jul 2008]

Canonical amino-acid sequenceUniProt

926 residues, UniProt reviewed canonical sequence.

>Q07617|SPAG1
     1  MTTKDYPSLW GFGTTKTFKI PIEHLDFKYI EKCSDVKHLE KILCVLRSGE EGYYPELTEF
    61  CEKHLQALAP ESRALRKDKP AATAASFTAE EWEKIDGDIK SWVSEIKKEE DKMHFHETET
   121  FPAMKDNLPP VRGSNSCLHV GKEKYSKRPT KKKTPRDYAE WDKFDVEKEC LKIDEDYKEK
   181  TVIDKSHLSK IETRIDTAGL TEKEKDFLAT REKEKGNEAF NSGDYEEAVM YYTRSISALP
   241  TVVAYNNRAQ AEIKLQNWNS AFQDCEKVLE LEPGNVKALL RRATTYKHQN KLREATEDLS
   301  KVLDVEPDND LAKKTLSEVE RDLKNSEAAS ETQTKGKRMV IQEIENSEDE EGKSGRKHED
   361  GGGDKKPAEP AGAARAAQPC VMGNIQKKLT GKAEGGKRPA RGAPQRGQTP EAGADKRSPR
   421  RASAAAAAGG GATGHPGGGQ GAENPAGLKS QGNELFRSGQ FAEAAGKYSA AIALLEPAGS
   481  EIADDLSILY SNRAACYLKE GNCSGCIQDC NRALELHPFS MKPLLRRAMA YETLEQYGKA
   541  YVDYKTVLQI DCGLQLANDS VNRLSRILME LDGPNWREKL SPIPAVPASV PLQAWHPAKE
   601  MISKQAGDSS SHRQQGITDE KTFKALKEEG NQCVNDKNYK DALSKYSECL KINNKECAIY
   661  TNRALCYLKL CQFEEAKQDC DQALQLADGN VKAFYRRALA HKGLKNYQKS LIDLNKVILL
   721  DPSIIEAKME LEEVTRLLNL KDKTAPFNKE KERRKIEIQE VNEGKEEPGR PAGEVSMGCL
   781  ASEKGGKSSR SPEDPEKLPI AKPNNAYEFG QIINALSTRK DKEACAHLLA ITAPKDLPMF
   841  LSNKLEGDTF LLLIQSLKNN LIEKDPSLVY QHLLYLSKAE RFKMMLTLIS KGQKELIEQL
   901  FEDLSDTPNN HFTLEDIQAL KRQYEL

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against SPAG1 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)
0.42
Highest tissue expression
18 nTPM

Expression across tissuesHPA

Tissue

  • testis: 18 nTPM
  • rectum: 17 nTPM
  • colon: 12 nTPM
  • choroid plexus: 10 nTPM
  • bone marrow: 9.6 nTPM
  • fallopian tube: 9.4 nTPM

Single-cell type

  • endometrial ciliated cells: 598 nCPM
  • respiratory ciliated cells: 456 nCPM
  • epididymal efferent duct ciliated cells: 452 nCPM
  • fallopian tube ciliated cells: 414 nCPM
  • ependymal cells: 413 nCPM
  • choroid plexus epithelial cells: 294 nCPM

Immune cell

  • NK-cell: 1 nTPM
  • memory B-cell: 0.8 nTPM
  • neutrophil: 0.7 nTPM
  • eosinophil: 0.6 nTPM
  • naive B-cell: 0.3 nTPM
  • non-classical monocyte: 0.2 nTPM

Brain region

  • choroid plexus: 30 nTPM
  • midbrain: 20 nTPM
  • medulla oblongata: 16 nTPM
  • spinal cord: 13 nTPM
  • pons: 12 nTPM
  • white matter: 12 nTPM

DiseaseUniProt · ClinVar · IEDB · PubMed

Four sources answering four different questions about SPAG1.

Disease | AllUniProt

Conditions SPAG1 is implicated in, by any mechanism.

  • Ciliary dyskinesia, primary, 28 (CILD28) MIM:615505

Disease | GeneticClinVar

70 pathogenic / likely-pathogenic of 623 ClinVar records.

Conditions with pathogenic or likely-pathogenic variants.

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)
0.76
gnomAD pLI
0
gnomAD missense Z
0.91
DepMap mean gene effect
0.04
DepMap dependency class
none

Cancer expressionTCGA

Across TCGA tumor cohorts, this protein is over-expressed in roughly 8% 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

Antibody and autoantibody relevanceSeroatlas analysis

Seroatlas reads SPAG1 as an antibody target. Whether an autoantibody or antibody against SPAG1 could matter depends on whether native SPAG1 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

SPAG1 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 agglutinating antibodies from an infertile woman.

Canonical record: https://seroatlas.com/gene/SPAG1. 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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