Expression of the cholecystokinin precursor gene in rat tissues.

Cholecystokinin, a brain gut peptide that stimulates gall bladder contraction and pancreatic exocrine secretion, also acts as a neurotransmitter. In this study, we demonstrated that small amounts of cholecystokinin precursor mRNA were expressed in the heart, lung, and kidney, as well as in the brain and the small intestine. The nucleotide sequences of the coding regions of the cholecystokinin precursor mRNA in these tissues were identical to those of the small intestine, indicating that cholecystokinin precursor proteins produced in these tissues are identical to those in small intestine. This is the first report demonstrating that the cholecystokinin precursor gene is expressed in the heart, lung, and kidney, as well as in the gastrointestinal tract and brain.