title: Maturational changes in terminal glycosylation of small intestinal microvillar proteins in the rat.
abstract: Studies were performed to identify rat intestinal microvillar proteins which undergo changes in terminal glycosylation during postnatal development. Pulse-labeling with [3H]fucose or N-[3H]acetylgalactosamine showed significantly higher incorporation into purified microvillar membranes of weanling than suckling rats. In contrast, the incorporation of [3H]sialic acid after pulse-labeling with N-[3H]acetylmanosamine was higher in suckling rats. SDS-polyacrylamide gel electrophoresis revealed these developmental differences in radioactive sugar incorporation to involve mainly proteins above Mr 90,000. 125I-labeled peanut lectin autoradiography revealed an Mr greater than 330,000 binding protein in suckling rats. Neuraminidase treatment of the membranes revealed the presence of sialyl-substituted sites in this protein in suckling, weaning and weanling animals, but the unmasking of sites decreased with advancing maturation. 125I-labeled Ulex europeus I autoradiography showed marked increases in binding of this lectin to Mr 66,000, 92,000, 130,000, 150,000 and greater than 330,000 proteins from weaning to weanling periods. Similar age-related increases in soybean lectin binding to Mr 130,000-150,000, and greater than 330,000 proteins were demonstrated by affinity chromatography. The Mr values of the major lectin-binding proteins were close to those reported for several hydrolases (trehalase, alkaline phosphatase, sucrase-isomaltase and glucoamylase). Comparison of the Coomassie blue-stained electrophoretograms from each age-group against the corresponding autoradiograms of lection-binding proteins led us to conclude that, while the content of these proteins in the membrane achieve their mature levels at or before weaning, their terminal glycosylation (desialylation, fucosylation, N-acetylgalactosamination) is not fully established until later development.
mesh_terms: D000375:Aging; D000818:Animals; D002458:Cell Fractionation; D006023:Glycoproteins / Q000096:biosynthesis / Q000302:isolation & purification; D006026:Glycoside Hydrolases / Q000378:metabolism*; D006867:Hydrolases / Q000378:metabolism*; D007421:Intestine, Small / Q000201:enzymology / Q000254:growth & development*; D008871:Microvilli / Q000201:enzymology* / Q000648:ultrastructure; D008970:Molecular Weight; D051381:Rats; D011919:Rats, Inbred Strains; D012794:Sialic Acids / Q000032:analysis
chemical_list: D006023:Glycoproteins; D012794:Sialic Acids; D006867:Hydrolases; D006026:Glycoside Hydrolases