Biosynthesis of intestinal microvillar proteins. Effect of castanospermine on cell-free synthesis of aminopeptidase N.
Pig small intestinal mRNA was translated in a rabbit reticulocyte lysate system supplemented with microsomal membranes. Castanospermine, an inhibitor of glucosidase I, induced a high mannose-glycosylated form of microvillar aminopeptidase N (EC 3.4.11.2) of increased molecular mass, indicating the blocked removal of glucose residues. In contrast to its reduced expression in a mucosal explant system [(1986) Biochem. J. 240, 777-782], this molecular form of aminopeptidase N was at least as abundant in cell-free translation as its normal high mannose-glycosylated counterpart, ruling out degradation taking place in the rough endoplasmic reticulum. Degradation of newly produced, malprocessed enzyme must therefore occur at a later stage during intracellular transport, presumably in the sarcoplasmic reticulum or in transitional elements between this organelle and the Golgi complex.
D000470:Alkaloids / Q000494:pharmacology*; D000626:Aminopeptidases / Q000096:biosynthesis*; D000818:Animals; D001665:Binding Sites; D018826:CD13 Antigens; D002474:Cell-Free System; D007212:Indolizines; D007421:Intestine, Small / Q000201:enzymology*; D008871:Microvilli / Q000201:enzymology; D012333:RNA, Messenger / Q000378:metabolism; D013552:Swine; D054836:Indolizidines
D000470:Alkaloids; D000626:Aminopeptidases; D018826:CD13 Antigens; D007212:Indolizines; D012333:RNA, Messenger; C037806:castanospermine; D054836:Indolizidines