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 an
d its complete nucleotide sequence determined. The full-length 1857 bp
sequence codes for a protein of 463 amino acid residues with a calcul
ated molecular mass of 51848 Da. Comparison of the deduced amino acid
sequence with that of rat preprocathepsin C indicates an 87.5% identit
y. A multiple alignment of the deduced cathepsin C sequence of 233 res
idues which, by analogy to other cysteine proteinases, corresponds to
the mature protein, confirms that human cathepsin C belongs to tbe pap
ain superfamily.