Tissue expression and immunolocalization of a novel human cathepsin P.

The mRNA of a novel human cathepsin P is expressed at high levels in lung, liver and heart. Using antibodies raised against recombinant cathepsin P produced in Escherichia coli, a single protein band of 33 kDa was detected by immunoblotting an extract of human liver. By immunofluorescence, positive signals were observed in hepatocytes and Kupffer cells of liver, and the distal tubule cells of kidney showing mainly perimembranous distribution, indicating a role, as yet unknown, for this novel putative protease that is distinct from other cathepsins of the papain family.