procolipase

Procolipase is the inactive precursor of colipase, a protein cofactor secreted by the pancreas that is essential for efficient digestion of dietary fats. It is produced by pancreatic acinar cells and released into the small intestine as part of pancreatic juice.

In the intestinal lumen, procolipase is activated by proteolytic enzymes, notably trypsin, which cleaves the propeptide to yield active colipase. The activation process removes an N-terminal propeptide, resulting in the mature form capable of supporting lipase activity.

Colipase serves as a non-enzymatic cofactor for pancreatic lipase. It binds to lipase and anchors it to the surface of lipid droplets in the presence of bile salts, enabling lipase to access triglycerides. This interaction stabilizes lipase at the lipid-water interface and enables efficient fat digestion, even when bile salt concentrations are high.

Physiological role: The procolipase-colipase-lipase system functions in the small intestine to facilitate digestion of dietary triglycerides. Activation and function are dependent on the intestinal environment and pancreatic secretion.

Clinical relevance: Defects in pancreatic exocrine function or impaired activation of procolipase can reduce fat digestion, leading to steatorrhea and fat-soluble vitamin deficiencies. Genetic variations affecting colipase expression or function have been investigated, but such conditions are uncommon compared with broader pancreatic insufficiency.