Molecular cloning and characterization of rabbit pancreatic triglyceride lipase

Abstract

Pancreatic lipase (triacylglycerol acylhydrolase, EC 3.1.1.3) has been cloned from a gt11 cDNA library made from poly A+ RNA of adult rabbit pancreas. Pancreatic lipase (PL) assists the absorption of dietary triglycerides by hydrolyzing them at 1 and 3 positions to free fatty acids and 2-monoacylglycerol in the presence of bile acids and colipase in the intestinal lumen. Since rabbits are classifically used for the study of the diet induced changes in the lipid metabolism, as a prelude to studying the diet and age dependent changes in the expression of this enzyme, a full length PL cDNA clone was obtained from its pancreas. The coding region of rabbit pancreatic lipase cDNA consists of 1407 base pairs contained in an open reading frame encoding 469 amino acids including the 16 that constitute the signal peptide. Northern blot analysis revealed a band around 1.5 kb. When rabbit enzyme is compared to other species, an over all homology of 70-80% was observed at the nucleotide level. High homology in the amino acid sequence and composition is also apparent between rabbit and other species like dog (65%), pig (76%) and rat (63%). Highest homology is found to be around active-site serine. The regions of homology with other species may help to define sites of interaction of lipase with co-lipase.