Modulation of the Expression Level of Human Acidic Lipases by Various Signal Peptides

Mammalian acidic lipases belong to a family of lipases that share the ability to maintain activity under acidic conditions. This family includes pre-duodenal lipases and lysosomal lipase and shows no sequence homology with other known lipase families (1 ,2 ). Human gastric lipase (glycerol ester hydrolase, EC 3.1.1.3, HGL) is secreted by chief cells of the fundic part of the stomach (3 ) where it initiates the digestion of triacylglycerols (4 ). Human lysosomal acid lipase (HLAL , EC 3.1.1.13) hydrolyzes cholesteryl esters and triglycerides that are delivered to the lysosomes by low density lipoprotein receptor-mediated endocytosis (5 ).