chymase 1(CMA1) Homo sapiens This gene encodes a chymotryptic serine proteinase that belongs to the peptidase family S1. It is expressed in mast cells and is thought to function in the degradation of the Extracellular matrix, the regulation of submucosal gland secretion, and the generation of vasoactive peptides. In the heart and blood vessels, this protein, rather than angiotensin converting enzyme, is largely responsible for converting angiotensin I to the vasoactive peptide angiotensin II. Alternative splicing results in multiple variants. [provided by RefSeq, Apr 2015]