Seroatlas · Human Serome Atlas

SPANXB1

Sperm protein associated with the nucleus on the X chromosome B1

Also known as: CT11.2, SPANXB2, SPANXF1, SPANXF2, SPNXB_HUMAN

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

Protein identityUniProt · HPA

UniProt accession
Q9NS25
Gene
SPANXB1
Ensembl
ENSG00000227234
Chromosome
X
Canonical length
103 aa
Protein class
Predicted intracellular proteins
Subcellular location
Nucleoplasm,Vesicles

OverviewNCBI Gene

Temporally regulated transcription and translation of several testis-specific genes is required to initiate the series of molecular and morphological changes in the male germ cell lineage necessary for the formation of mature spermatozoa. This gene is a member of the SPANX family of cancer/testis-associated genes, which are located in a cluster on chromosome X. The SPANX genes encode differentially expressed testis-specific proteins that localize to various subcellular compartments. This particular family member contains an additional 18 nucleotides in its coding region compared to the other family members in the same gene cluster. This family member is also subject to gene copy number variation. Although the protein encoded by this gene contains consensus nuclear localization signals, the major site for subcellular localization of expressed protein is in the cytoplasmic droplets of ejaculated spermatozoa. This protein provides a biochemical marker for studying the unique structures in spermatazoa, while attempting to further define its role in spermatogenesis. [provided by RefSeq, Apr 2014]

Canonical amino-acid sequenceUniProt

103 residues, UniProt reviewed canonical sequence.

>Q9NS25|SPANXB1
     1  MGQQSSVRRL KRSVPCESNE ANEANEANKT MPETPTGDSD PQPAPKKMKT SESSTILVVR
    61  YRRNVKRTSP EELLNDHARE NRINPDQMEE EEFIEITTER PKK

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against SPANXB1 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)
0.62
Highest tissue expression
87 nTPM

Expression across tissuesHPA

Tissue

  • testis: 87 nTPM
  • tongue: 1 nTPM
  • adipose tissue: 0.6 nTPM
  • kidney: 0.3 nTPM
  • adrenal gland: 0 nTPM
  • amygdala: 0 nTPM

Single-cell type

  • late spermatids: 2,940 nCPM
  • early spermatids: 731 nCPM
  • late primary spermatocytes: 224 nCPM
  • sertoli cells: 6.2 nCPM
  • epididymal clear cells: 2 nCPM
  • leydig cells: 2 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

  • white matter: 1.7 nTPM
  • cerebral cortex: 1.3 nTPM
  • hypothalamus: 1.1 nTPM
  • basal ganglia: 1 nTPM
  • medulla oblongata: 1 nTPM
  • pons: 1 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.

DepMap mean gene effect
-0.01
DepMap dependency class
selective

OntologyGO

Biological processes

Cellular components

Protein domainsUniProt · Pfam · InterPro

KeywordsUniProt

Antibody and autoantibody relevanceSeroatlas analysis

Seroatlas reads SPANXB1 as an antibody target. Whether an autoantibody or antibody against SPANXB1 could matter depends on whether native SPANXB1 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

SPANXB1 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.

Annotation status

The present source text does not explicitly label SPANXB1 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

Canonical record: https://seroatlas.com/gene/SPANXB1. 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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