Seroatlas · Human Serome Atlas

CTSO

Cathepsin O

Also known as: CATO_HUMAN, CTSO1

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

Protein identityUniProt · HPA

UniProt accession: P43234
Gene: CTSO
Ensembl: ENSG00000256043
Chromosome: 4
Canonical length: 321 aa
Protein class: Enzymes, Metabolic proteins, Predicted intracellular proteins
Secretome location: Intracellular and membrane

OverviewNCBI Gene

The protein encoded by the gene is a cysteine proteinase and a member of the papain superfamily. This proteolytic enzyme is involved in cellular protein degradation and turnover. The recombinant form of this enzyme was shown to degrade synthetic peptides typically used as substrates for cysteine proteinases and its proteolytic activity was abolished by an inhibitor of cyteine proteinase. [provided by RefSeq, Jul 2008]

Canonical amino-acid sequenceUniProt

321 residues, UniProt reviewed canonical sequence.

>P43234|CTSO
     1  MDVRALPWLP WLLWLLCRGG GDADSRAPFT PTWPRSRERE AAAFRESLNR HRYLNSLFPS
    61  ENSTAFYGIN QFSYLFPEEF KAIYLRSKPS KFPRYSAEVH MSIPNVSLPL RFDWRDKQVV
   121  TQVRNQQMCG GCWAFSVVGA VESAYAIKGK PLEDLSVQQV IDCSYNNYGC NGGSTLNALN
   181  WLNKMQVKLV KDSEYPFKAQ NGLCHYFSGS HSGFSIKGYS AYDFSDQEDE MAKALLTFGP
   241  LVVIVDAVSW QDYLGGIIQH HCSSGEANHA VLITGFDKTG STPYWIVRNS WGSSWGVDGY
   301  AHVKMGSNVC GIADSVSSIF V

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against CTSO 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: 92 nTPM

Expression across tissuesHPA

Tissue

liver: 92 nTPM
placenta: 39 nTPM
gallbladder: 38 nTPM
spleen: 37 nTPM
ovary: 35 nTPM
endometrium: 35 nTPM

Single-cell type

oligodendrocyte progenitor cells: 52 nCPM
bergmann glia: 27 nCPM
astrocytes: 24 nCPM
ependymal cells: 19 nCPM
microglia: 19 nCPM
loop of henle epithelial cells: 18 nCPM

Immune cell

basophil: 5.2 nTPM
T-reg: 3.3 nTPM
MAIT T-cell: 3 nTPM
NK-cell: 2.9 nTPM
naive CD8 T-cell: 2 nTPM
naive B-cell: 1.5 nTPM

Brain region

cerebral cortex: 20 nTPM
choroid plexus: 20 nTPM
midbrain: 19 nTPM
amygdala: 19 nTPM
basal ganglia: 19 nTPM
hypothalamus: 19 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): 1.33
gnomAD pLI: 0
gnomAD missense Z: -0.1
DepMap mean gene effect: 0.04
DepMap dependency class: none

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

cysteine-type endopeptidase activity

Cellular components

Protein domainsUniProt · Pfam · InterPro

KeywordsUniProt

Antibody and autoantibody relevanceSeroatlas analysis

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

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

Loading the interactive Seroatlas protein explorer...