Seroatlas · Human Serome Atlas

CASTOR1

Cytosolic arginine sensor for mTORC1 subunit 1

Also known as: CAST1_HUMAN, GATSL3

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

Protein identityUniProt · HPA

UniProt accession: Q8WTX7
Gene: CASTOR1
Ensembl: ENSG00000239282
Chromosome: 22
Canonical length: 329 aa
Protein class: Predicted intracellular proteins
Quaternary structure: Homodimer

OverviewNCBI Gene

Enables several functions, including arginine binding activity; identical protein binding activity; and protein sequestering activity. Involved in cellular response to L-arginine; cellular response to amino acid starvation; and regulation of TORC1 signaling. Located in GATOR2 complex and cytosol. [provided by Alliance of Genome Resources, Jul 2025]

Canonical amino-acid sequenceUniProt

329 residues, UniProt reviewed canonical sequence.

>Q8WTX7|CASTOR1
     1  MELHILEHRV RVLSVARPGL WLYTHPLIKL LFLPRRSRCK FFSLTETPED YTLMVDEEGF
    61  KELPPSEFLQ VAEATWLVLN VSSHSGAAVQ AAGVTKIARS VIAPLAEHHV SVLMLSTYQT
   121  DFILVREQDL SVVIHTLAQE FDIYREVGGE PVPVTRDDSS NGFPRTQHGP SPTVHPIQSP
   181  QNRFCVLTLD PETLPAIATT LIDVLFYSHS TPKEAASSSP EPSSITFFAF SLIEGYISIV
   241  MDAETQKKFP SDLLLTSSSG ELWRMVRIGG QPLGFDECGI VAQIAGPLAA ADISAYYIST
   301  FNFDHALVPE DGIGSVIEVL QRRQEGLAS

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against CASTOR1 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): 0.27
Highest tissue expression: 51 nTPM

Expression across tissuesHPA

Tissue

esophagus: 51 nTPM
vagina: 36 nTPM
cervix: 30 nTPM
testis: 18 nTPM
basal ganglia: 17 nTPM
amygdala: 15 nTPM

Single-cell type

cytotrophoblasts: 88 nCPM
esophageal apical cells: 88 nCPM
extravillous trophoblasts: 78 nCPM
esophageal suprabasal cells: 68 nCPM
migrating cytotrophoblasts: 47 nCPM
syncytiotrophoblasts: 36 nCPM

Immune cell

NK-cell: 29 nTPM
naive CD4 T-cell: 22 nTPM
eosinophil: 20 nTPM
naive B-cell: 16 nTPM
naive CD8 T-cell: 16 nTPM
memory B-cell: 16 nTPM

Brain region

midbrain: 11 nTPM
thalamus: 10 nTPM
hypothalamus: 9.9 nTPM
amygdala: 9.6 nTPM
basal ganglia: 9.4 nTPM
medulla oblongata: 8.9 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): 0.75
gnomAD pLI: 0.03
DepMap mean gene effect: -0.19
DepMap dependency class: selective

Cancer expressionTCGA

Across TCGA tumor cohorts, this protein is over-expressed in roughly 4% of surveyed tumor types (aggregate summary; per-cohort expression, alteration, and survival load in the interactive view).

OntologyGO

Biological processes

Molecular functions

Cellular components

cytosol

Protein domainsUniProt · Pfam · InterPro

KeywordsUniProt

InteractionsUniProt · HPA

Protein binding partners of CASTOR1 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 CASTOR1 as an antibody target. Whether an autoantibody or antibody against CASTOR1 could matter depends on whether native CASTOR1 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

CASTOR1 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 CASTOR1 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

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