title: Analysis of galactosyltransferase activity in rat gastric mucosa using crude mucosal homogenate.
abstract: Mucus glycoprotein is one of the major components of gastric mucus which plays an important role in mucosal defensive mechanisms as a mucus-bicarbonate barrier. Analysis of the mucus glycoprotein synthesis is a useful tool for evaluating gastric mucosal defensive factors. UDP-galactosyltransferase (UDP-Gal-T) is one of the regulating enzymes for the synthesis of the mucus glycoprotein. In the present paper, we studied assay methods for UDP-Gal-T activity in rat gastric mucosa using radiolabeled UDP-galactose and two different kinds of acceptor proteins, namely ovomucoid and asialomucin, and analyzed effects of antisecretory agents on the UDP-Gal-T activity. We used crude supernatants of homogenized scrapings of the fundic part of rat stomach as an enzyme preparation and determined optimal conditions. In each acceptor, Mn2+ and the non-ionic detergent Triton X-100 were required for the enzyme activity. With each acceptor molecule, the type of glycosidic linkages of galactose was beta-type linkage. With asialomucin as an acceptor, UDP-Gal-T activities of rat gastric mucosa decreased after intraperitoneal administration of antisecretory agents, while change of the enzyme activity was not observed with ovomucoid as an acceptor.
authors.affiliation: First Department of Internal Medicine, Okayama University Medical School, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Hongo
authors.forename: J
authors.initials: J
authors.lastname: Tomoda
authors.forename: M
authors.initials: M
authors.lastname: Mizuno
authors.forename: T
authors.initials: T
authors.lastname: Maga
authors.forename: T
authors.initials: T
authors.lastname: Tsuji
mesh_terms: D000818:Animals; D005700:Galactosyltransferases / Q000032:analysis*; D005753:Gastric Mucosa / Q000201:enzymology*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D005700:Galactosyltransferases