EC - Cathepsin O

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IntEnz Enzyme Nomenclature


Accepted name:
cathepsin O
Systematic name:



Cathepsin O is a lysosomal cysteine peptidase of family C1 (papain family). The recombinant human enzyme is catalytically active at pH 6.0 and is inhibited by compound E-64. Cathepsin O is ubiquitously expressed in human tissues and the human gene locus is 4q31-32.

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , MEROPS , UniPathway
Protein domains and families: PROSITE:PDOC00126
Structural data: CSA , EC2PDB


  1. Santamaría, I., Pendás, A.M., and López-Otín, C.
    Genomic structure and chromosomal localization of a human cathepsin O gene (CTSO).
    Genomics 53: 231-234 (1998). [PMID: 9790772]
  2. Velasco, G., Ferrando, A.A., Puente, X.S., Sanchez, L.M. and López-Otín, C.
    Human cathepsin O. Molecular cloning from a breast carcinoma, production of the active enzyme in Escherichia coli, and expression analysis in human tissues.
    J. Biol. Chem. 269: 27136-27142 (1994). [PMID: 7929457]

[EC created 2000]