Chymotrypsin C (CTRC)

Elastase 4 is a member of the peptidase S1 family. The encoded protein is a serum calcium-decreasing factor that has chymotrypsin-like protease activity. Alternatively spliced transcript variants have been observed, but their full-length nature has not been determined. These human caldecrin isoforms, like the rat preproenzyme, are composed of a signal peptide of 16 amino acids, a propeptide of 13 amino acids, and a mature form of 239 amino acids. Both recombinant caldecrins, produced in a baculovirus expression system, showed the same chymotrypsin-type protease activity and hypocalcemic activity. The hypocalcemic activity of both caldecrin isoforms remained intact even after treatment with phenylmethylsulfonyl fluoride (PMSF) to abolish their protease activity.