Isolation and partial characterization of rat gastric mucous glycoprotein

Abstract

SummaryMucus glycoproteins from the rat stomach were characterized after their isolation from homogenates of the superficial gastric mucosa by equilibrium centrifugation in CsC1 density gradients. Water-soluble as well as water-insoluble glycoproteins were studied. The latter were solubilized by 2-mercaptoethanol reduction of the homogenate. From both homogenate fractions the same two glycoproteins 1 and 2 were purified, glycoprotein 1 being present in considerably higher amount than glycoprotein 2. Their respective buoyant densities in a CsC1 gradient were 1.47--1.50 g/ml and 1.56--1.58 g/ml. The two glycoproteins expressed slight differences in gel electrophoresis and gel filtration. The results from column chromatographic comparisons between reduced and unreduced glycoproteins indicated strongly that both glycoproteins 1 and 2 were built from subunits kept together by S-S bonds. The s20,w values of the reduced glycoproteins 1 and 2 were 15.7 S and 11.6 S. Glycoprotein 1 contained 5% protein, 70% carbohydrate and 1--2% sulphate, whereas these percentages for glycoprotein 2 were 10% protein, 65% carbohydrate and 10% sulphate. The molar proportions of the main sugar components galactose, fucose, glucosamine and galactosamine were 4 : 2 : 4 : 1 (glycoprotein 1) and 3 : 2 : 3 : 1 (glycoprotein 2). Blood-group activity A was expressed by glycoprotein 1, whereas glycoprotein 2 showed mainly blood-group activity Le b, some B activity and also some A activity, but to a lesser extent than glycoprotein 1.

Age and Diet Affect the Composition of Porcine Colonic Mucins

“…The sulfate content was greater in mucin from newborn rats (5.5 versus 0.9%). The decrease in sulfate content with age is consistent with the speculation that a higher degree of sulfation is characteristic of mucous glycoproteins secreted by "immature" goblet cells (25). The developmental changes in rat small-intestinal mucin are similar to those in our study of pig colonic mucin.…”

Types of oligosaccharide sulphation, depending on mucus glycoprotein source, corpus or antral, in rat stomach

“…35S-labelled macromolecules were also obtained from the culture medium by Bio-Gel A-1.5m chromatography. These macromolecules were further purified by CsCl centrifugation to remove nucleic acids and proteins (Spee-Brand et al, 1980). Fig.…”

Glycoprotein synthesis in the mucous cells of the vascularly perfused rat stomach. III. Mucous cells of the antrum and the duodenal glands

“…The relatively low synthetic activity of the mucous cells of antral glands correlates well with the various amounts of RER, Golgi system, and secretory granules, found in these cells, and with the histochemical staining characteristics of their mucous granules. The mucous cells of the duodenal glands are characterized by typical parallel arrays of their numerous RER cisternae and by a low number of small secretory granules.Glycoproteins from various regions along the gastrointestinal tract have been isolated and characterized in man and various animals, including the stomach (Spee-Brand et al, 1980) and the small intestine (Forstner et al, 1973;Wold et al, 1974) of the rat. However, little is known about the secretory glycoproteins synthesized by the various mucous cells in the antrum of the stomach and the duodenal glands.…”