Cathepsin O

CTSO (gene locus)
cathepsin O1 (CTSO1)

Gene: CTSO maps to 4q31-q32. The gene is composed of eight coding exons and seven introns and spans more than 30 kb. The number and distribution of exons and introns differ from those reported for other human cysteine proteinases, indicating that these genes are not closely related (Santamaría I. et al., 1998).
mRNA: size: 1.7 kb (Shi G.P. et al., 1995). It is expressed in a variety of tissues, which is consistent with a putative role of this protein as a proteolytic enzyme involved in normal cellular protein degradation and turnover.
Protein: a 321-amino acids cysteine proteinase isolated from a human breast carcinoma cDNA library. After expression in Escherichia coli, purification, and refolding, the recombinant protein was found to degrade synthetic peptides widely used as substrates for cysteine proteinases. Furthermore, CTSO proteolytic activity was abolished by an inhibitor of this subclass of proteolytic enzymes (Velasco G. et al., 1994).

Cell lines:

Tumors:
- Cathepsin O was cloned from a human breast carcinoma cDNA library, by using a polymerase chain reaction-based cloning strategy (Velasco G. et al., 1994).

Santamaría I. et al. (1998) Genomic structure and chromosomal localization of the human cathepsin O gene (CTSO). Genomics 53, 231-234.
Shi G.P. et al. (1995) Molecular cloning of human cathepsin O, a novel endoproteinase and homologue of rabbit OC2. FEBS Lett. 357, 129-134.
Velasco G. et al. (1994) 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.

Cathepsin B, cathepsin D, cathepsin K, cathepsin L2