Seroatlas · Human Serome Atlas

CTSS

Cathepsin S

Also known as: CATS_HUMAN

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

Protein identityUniProt · HPA

UniProt accession
P25774
Gene
CTSS
Ensembl
ENSG00000163131
Chromosome
1
Canonical length
331 aa
Protein class
Enzymes, Metabolic proteins, Plasma proteins, Predicted intracellular proteins
Subcellular location
Vesicles
Secretome location
Intracellular and membrane

OverviewNCBI Gene

The preproprotein encoded by this gene, a member of the peptidase C1 family, is a lysosomal cysteine proteinase that participates in the degradation of antigenic proteins to peptides for presentation on MHC class II molecules. The mature protein cleaves the invariant chain of MHC class II molecules in endolysosomal compartments and enables the formation of antigen-MHC class II complexes and the proper display of extracellular antigenic peptides by MHC-II. The mature protein also functions as an elastase over a broad pH range. When secreted from cells, this protein can remodel components of the extracellular matrix such as elastin, collagen, and fibronectin. This gene is implicated in the pathology of many inflammatory and autoimmune diseases and, given its elastase activity, plays a significant role in some pulmonary diseases. Alternatively spliced transcript variants encoding distinct isoforms have been found for this gene. [provided by RefSeq, May 2020]

Canonical amino-acid sequenceUniProt

331 residues, UniProt reviewed canonical sequence.

>P25774|CTSS
     1  MKRLVCVLLV CSSAVAQLHK DPTLDHHWHL WKKTYGKQYK EKNEEAVRRL IWEKNLKFVM
    61  LHNLEHSMGM HSYDLGMNHL GDMTSEEVMS LMSSLRVPSQ WQRNITYKSN PNRILPDSVD
   121  WREKGCVTEV KYQGSCGACW AFSAVGALEA QLKLKTGKLV SLSAQNLVDC STEKYGNKGC
   181  NGGFMTTAFQ YIIDNKGIDS DASYPYKAMD QKCQYDSKYR AATCSKYTEL PYGREDVLKE
   241  AVANKGPVSV GVDARHPSFF LYRSGVYYEP SCTQNVNHGV LVVGYGDLNG KEYWLVKNSW
   301  GHNFGEEGYI RMARNKGNHC GIASFPSYPE I

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against CTSS 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
Secreted
Secreted
Yes
Transmembrane segments
0
Mean surface accessibility (rSASA)
0.26
Highest tissue expression
128 nTPM

Expression across tissuesHPA

Tissue

  • spleen: 128 nTPM
  • bone marrow: 122 nTPM
  • appendix: 82 nTPM
  • colon: 78 nTPM
  • lung: 70 nTPM
  • lymph node: 67 nTPM

Single-cell type

  • kupffer cells: 2,999 nCPM
  • monocytes: 2,663 nCPM
  • neutrophils: 1,730 nCPM
  • macrophages: 1,043 nCPM
  • neutrophil progenitors: 829 nCPM
  • cdc: 622 nCPM

Immune cell

  • total PBMC: 2,556 nTPM
  • classical monocyte: 2,462 nTPM
  • intermediate monocyte: 1,718 nTPM
  • non-classical monocyte: 1,642 nTPM
  • neutrophil: 1,016 nTPM
  • myeloid DC: 565 nTPM

Brain region

  • white matter: 36 nTPM
  • medulla oblongata: 27 nTPM
  • pons: 26 nTPM
  • thalamus: 25 nTPM
  • spinal cord: 20 nTPM
  • choroid plexus: 18 nTPM

DiseaseUniProt · ClinVar · IEDB · PubMed

Four sources answering four different questions about CTSS.

Disease | ImmuneIEDB

Conditions an epitope on CTSS 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)
0.53
gnomAD pLI
0.34
gnomAD missense Z
2.24
DepMap mean gene effect
-0.04
DepMap dependency class
selective

Cancer expressionTCGA

Across TCGA tumor cohorts, this protein is over-expressed in roughly 5% 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 CTSS as an antibody target. Whether an autoantibody or antibody against CTSS could matter depends on whether native CTSS is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

CTSS is annotated as secreted, so native CTSS circulates and is directly accessible to antibodies. Secreted and cell-surface proteins are the autoantibody targets most likely to act like drugs, blocking or depleting the native protein.

Source-annotated serology context

The source annotations explicitly mention antibody, autoantibody, autoantigen, or autoimmune context. This is biological context, not study-specific reactivity.

  • This gene is implicated in the pathology of many inflammatory and autoimmune diseases and, given its elastase activity, plays a significant role in some pulmonary diseases.

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