Identification and molecular cloning of cathepsin P, a novel human putative cysteine protease of the papain family

A cDNA encoding a novel human putative member of the papain family of cyste ine peptidases has been cloned. The protease, named cathepsin P, is synthes ized as a preproprotein. The presumed propeptide of 38 amino acids is follo wed by a 242-residue mature protein. The mature protease region is 30% iden tical to human papain-like cathepsins, with all the residues important for catalysis conserved. No similarity was observed in the propeptide region. O n the contrary, the proenzyme shares 51-87% residues with some precursors o f cysteine proteases from other species that have not yet been characterize d. They all show a nearly completely conserved "CYTRED motif" in the propep tide region, not present in other members of the family, and could therefor e constitute a distinct subfamily.