Seroatlas · Human Serome Atlas

CT55

Cancer/testis antigen 55

Also known as: CT55_HUMAN, CXorf48, FLJ20527

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

Protein identityUniProt · HPA

UniProt accession
Q8WUE5
Gene
CT55
Ensembl
ENSG00000169551
Chromosome
X
Canonical length
264 aa
Protein class
Predicted intracellular proteins
Subcellular location
Vesicles

OverviewNCBI Gene

Involved in spermatogenesis. Located in acrosomal vesicle and sperm flagellum. Implicated in X-linked spermatogenic failure 7. [provided by Alliance of Genome Resources, Jul 2025]

Canonical amino-acid sequenceUniProt

264 residues, UniProt reviewed canonical sequence.

>Q8WUE5|CT55
     1  MLRLLRLALA FYGRTADPAE RQGPQQQGLP QGDTQLTTVQ GVVTSFCGDY GMIDESIYFS
    61  SDVVTGNVPL KVGQKVNVVV EEDKPHYGLR AIKVDVVPRH LYGAGPSDSG TRVLIGCVTS
   121  INEDNIYISN SIYFSIAIVS EDFVPYKGDL LEVEYSTEPG ISNIKATSVK PIRCIHTEEV
   181  CITSVHGRNG VIDYTIFFTL DSVKLPDGYV PQVDDIVNVV MVESIQFCFI WRAISITPVH
   241  KSSSGFQDDG GLGRPKRERR SQSI

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against CT55 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)
0.39
Highest tissue expression
3.6 nTPM

Expression across tissuesHPA

Tissue

  • testis: 3.6 nTPM
  • basal ganglia: 0.3 nTPM
  • cerebral cortex: 0.3 nTPM
  • hippocampal formation: 0.3 nTPM
  • amygdala: 0.2 nTPM
  • hypothalamus: 0.2 nTPM

Single-cell type

  • early primary spermatocytes: 16 nCPM
  • differentiating spermatogonia: 7.8 nCPM
  • adipocytes: 2.7 nCPM
  • brain inhibitory neurons: 0.9 nCPM
  • cardiomyocytes: 0.7 nCPM
  • other brain neurons: 0.7 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: 1.7 nTPM
  • hippocampal formation: 1.1 nTPM
  • amygdala: 1 nTPM
  • basal ganglia: 1 nTPM
  • white matter: 1 nTPM
  • thalamus: 0.9 nTPM

DiseaseUniProt · ClinVar · IEDB · PubMed

Four sources answering four different questions about CT55.

Disease | AllUniProt

Conditions CT55 is implicated in, by any mechanism.

  • Spermatogenic failure, X-linked, 7 (SPGFX7) MIM:301106

Disease | GeneticClinVar

1 pathogenic / likely-pathogenic of 14 ClinVar records.

Conditions with pathogenic or likely-pathogenic variants.

Disease | ImmuneIEDB

Conditions an epitope on CT55 was assayed in.

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)
0.8
gnomAD pLI
0.49
gnomAD missense Z
0.84
DepMap mean gene effect
0.11
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 CT55 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 CT55 as an antibody target. Whether an autoantibody or antibody against CT55 could matter depends on whether native CT55 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

CT55 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 CT55 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

Canonical record: https://seroatlas.com/gene/CT55. 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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