A cDNA clone (C1) coding for human preprocathepsin C was isolated from a human ileum cDNA library using a rat kidney-derived RT-PCR probe and its complete nucleotide sequence determined. The full-length 1857 bp sequence codes for a protein of 463 amino acid residues with a calculated molecular mass of 51848 Da. Comparison of the deduced amino acid sequence with that of rat preprocathepsin C indicates an 87.5% identity. A multiple alignment of the deduced cathepsin C sequence of 233 residues which, by analogy to other cysteine proteinases, corresponds to the mature protein, confirms that human cathepsin C belongs to the papain superfamily.
