title: Lipid-deprived diet perturbs O-glycosylation of secretory proteins in rat mammary epithelial cells.
abstract: Nutrition modulates both production and composition of milk. Milk composition was studied in rats chronically fed a diet without additional lipids, and therefore eating only traces of the recommended supply of essential polyunsaturated fatty acid. Despite a large decrease in milk-protein synthesis, only protein composition, but not protein concentration, was found to change in the milk of rats following a lipid-deprived diet. Correlatively, we observed a substantial increase in the lactose concentration of milk. Analysis of milk proteins by two-dimensional electrophoresis demonstrated that the relative proportion of the various molecular forms of κ-casein, an O-glycosylated protein, was modified in the milk of rats receiving the lipid-deprived diet. In tissues, differences in the two-dimensional pattern of κ-casein between control and lipid-deprived rats were similar, if not identical. In contrast to κ-casein, the molecular forms of α-lactalbumin, an N-glycosylated protein, were not affected by the diet. These data provide evidence that O-glycosylation of milk proteins in the secretory pathway of mammary epithelial cells is modulated by the lipid content of experimental diets.
authors.affiliation: INRA, U1196 Génomique et Physiologie de la Lactation, Domaine de Vilvert, F-78352 Jouy-en-Josas Cedex, France.
authors.forename: F
authors.initials: F
authors.lastname: Lavialle
authors.forename: E
authors.initials: E
authors.lastname: Chanat