CTRC is the acronym for "Chymotrypsin C". The CTRC gene is located on chromosome 1p36.21. It comprises 8 exons spanning 8.2 kb and encodes a member of the peptidase S1 family. The encoded protein (pre-chymotrypsinogen C) is a serum calcium-reducing factor that has chymotrypsin-like protease activity (Rosendahl J et al. 2008; Masson E et al. 2008). It consists of a secretory signal peptide of 16 amino acids, a propeptide (activation peptide) of 13 amino acids and a chymotrypsin-like enzyme of 239 amino acids. CTRC is a digestive protease synthesized and secreted by pancreatic acinar cells as an inactive proenzyme (zymogen) that is activated in the duodenum after tryptic cleavage of the Arg29-Val30 peptide bond at the C-terminal end of the propeptide.
CTRC is the same protein as caldecrin, a serum calcium-lowering protein isolated from porcine and rat pancreas and later cloned from rat and human pancreas, although the identity of these two proteins has not been formally established. The protease activity of CTRC and its effect on calcium homeostasis appear to be distinct and unrelated functions, although both require activation by trypsin (Zhou J et al. 2012)