Cathepsin-Z (CTSZ) is a lysosomal cysteine proteinase and member of the peptidase C1 family. CTSZ, which has been also known as cathepsin X and cathepsin P, exhibits carboxy-monopeptidase and carboxy-dipeptidase activities. CTSZ is expressed ubiquitously in cancer cell lines and primary tumors and, similar to other members of this family, takes part in tumorigenesis.

CTSZ produced in Sf9 Baculovirus cells is a single, glycosylated polypeptide chain containing 292 amino acids (23-306a.a.) and having a molecular mass of 32.8kDa. (Molecular size on SDS-PAGE will appear at approximately 28-40kDa). CTSZ is expressed with an 8 amino acid His tag at C-Terminus and purified by proprietary chromatographic techniques.