Chymotrypsinogen B1 (or sometimes just Chymotrypsinogen B) is a protein that in humans is encoded by the CTRB1 gene. Similar to its paralog chymotrypsinogen B2, chymotrypsiongen B1 is an inactive precursor for an enzyme which is an isozyme of chymotrypsin. It is secreted by the acinar cells of the pancreas into the small intestines as part of pancreatic juice, where it is activated. After activation it functions as a protease which is involved in breaking down other proteins as part of digestion.
Medical significance The CTRB1 and CTRB2 genes are located near each other on chromosome 16. In some populations there is an inversion which causes certain parts of each gene to be swapped, which has been associated with an increased risk of chronic pancreatitis.
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