Properties and function of pancreatic lipase related protein 2

The lipase gene family includes pancreatic triglyceride lipase and two panc reatic proteins, pancreatic lipase related proteins 1 and 2, with strong nu cleotide and amino acid sequence homology to pancreatic triglyceride Lipase . All three proteins have virtually identical three-dimensional structures. Of the pancreatic triglyceride lipase homologues, only pancreatic lipase r elated protein 2 has lipase activity. Like pancreatic triglyceride Lipase, related protein 2 cleaves triglycerides, but it has broader substrate speci ficity. Pancreatic lipase related protein 2 also hydrolyzes phospholipids a nd galactolipids, two fats that are not substrates for pancreatic triglycer ide lipase. The rat-related protein 2 also differs from pancreatic triglyce ride lipase in sensitivity to bile salts and in response to colipase. Altho ugh the pancreas expresses both lipases, their temporal pattern of expressi on differs. Pancreatic lipase-related protein 2 mRNA appears before birth a nd persists into adulthood, whereas PTL mRNA first appears at the suckling- weanling transition. Additionally, intestinal enterocytes, paneth cells and cultured cytotoxic T-cells express mRNA encoding pancreatic lipase related protein 2. A physiological function for pancreatic lipase related protein 2 was demonstrated in mice that did not express this protein. Pancreatic li pase related protein 2 deficient mice malabsorbed fat in the suckling perio d, but not after weaning. They also had a defect in T-cell mediated cytotox icity. Thus, pancreatic lipase related protein 2 isa lipase that participat es in the cytotoxic activity of T-cells and plays a critical role in the di gestion of breast milk fats. (C) 2000 Societe francaise de biochimie et bio logie moleculaire / Editions scientifiques et medicales Elsevier SAS.