Impairment of plasma glycoprotein synthesis in choline deficiency compared with effects of carbon tetrachloride intoxication

Abstract

The incorporation of glucosamine-1-¹⁴C into plasma proteins is impaired in rats within 2 days when they are fed a choline-deficient diet. Separation of plasma proteins by starch-gel electrophoresis, and autoradiography of the dried gels, showed four labelled areas (glycoproteins). In choline deficiency there was visual evidence of depletion of radioactivity in the fast α-globulin area, a finding confirmed by the specific radioactivity of proteins eluted from electrophoretic zones of the starch gel. Within 4 h after ingestion of carbon tetrachloride, the synthesis of plasma glycoprotein was reduced by 90% and labelling of all four glycoprotein areas on dried starch gel autoradiograms virtually ceased. The results suggest that the defect in glycoprotein synthesis in carbon tetrachloride intoxication is nonspecific, whereas in choline deficiency the impairment is specific and localized in the fast α-globulin fraction. The results suggest a limiting role of a glycoprotein in the pathway of plasma lipoprotein synthesis.