Biosynthesis of a Fucose-containing Glycopeptide from Rat Small Intestine in Normal and Vitamin A-deficient Conditions

Abstract

Abstract The number of goblet cells in the small intestine decreased in the vitamin A-deficient rat. Incorporation of 14C-d-glucosamine into a fucose-containing glycopeptide declined markedly. Ultracentrifugation of this glycopeptide in H2O gave only a single component, with a sedimentation value of 3.6 S, whereas, in 0.1 m phosphate buffer (pH 7.5) two components appeared, with much higher sedimentation constants (6.2 S and 7.2 S). The glycopeptide was found to contain glucosamine, galactose, fucose, and sialic acid in the molar ratios of 3:3:1:0.25, respectively. Synthesis of the fucose-containing glycopeptide in vitro, using uridine-diphosphate-N-acetyl-d-glucosamine-1-14C and 3H-serine, showed a 2- to 3-fold decrease in the incorporation of the labels by rough endoplasmic reticulum prepared from vitamin A-deficient animals as compared with normal animals.