Synthesis of Mucus Glycoprotein in Ribosome of Rat Gastric Mucous Cell.

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Using gastric mucous cells which are involved exclusively in the synthesis of secretory O-glycosidic glycoprotein (mucin), the relationships between protein core synthesis and its acylation with fatty acids, O-glycosylation with N-acetylgalactosamine were investigated Labeling of the cells with[^3H]-proline, [^3H]-palmitic acid, [^<14>C]-galactosamine followed by isolation of peptidy -tRNA and release of nascent peptides indicated that the nascent peptide were already glycosylated and acylated in the ribosome of the rat gastric mucous cell.1. Prevention of alcohol-induced gastric mucosal injury by prostaglandin E-1 Effects of ethanol and prostaglandin on the glycoprotein synthesis in the gastric mucus cells have been evaluated. The rat gastric mucosal cells were subjected to a short-term tissue culture in the presence of ehtanol and prostaglandin El using[^3H]-proline, [^3H]-Palmitic acid, [^<14>C]-galactosamine. Low concentration of ehtanol (0.05-0.1M) stimulated the glycoprotein synt … More hesis, but higher concentration of ehtanol (0.5-1.5M) caused a marked reduction in the glycoprotein synthesis. Addition of prostaglandin resulted in the stabilization of the synthesis and secretion of the mucucs glycoprotein in the presence of ethanol.2. lnfluence of water-immersion stress on synthesis of mucus glycoprotein in rat gastric mucosa.Gastric raucous cells of rats subjected to water immersion stress were incubated with[^3H]-palmitic acid and[^<14>C]-N-acetylgalactosamine. The peptdyl-tRNA released by gastric polysomes was precipitated with cold ethanol and then the content was determined. A 70% reduction in the peptidyltRNA isolated was observed in the stress rats, as compared with in control rat. The peptide recoverd from the peptidyl-tRNA showed 30-50% less[3H]-Palmitic acid and[^<14>C]- N-acetylgalactosamine incorporation in the stressed rats than in normal control. It was thus suggested that translation, acylation and glycosylation of the peptides in the ribosomes of the gastric mucosa were remarkably affected by the stress. Less