A UDP-glucose:glycoprotein glucose-1-phosphotransferase in embryonic chicken neural retina

Cell. 1982 Dec;31(3 Pt 2):739-48. doi: 10.1016/0092-8674(82)90328-2.

Abstract

A subclass of cell-surface glycoproteins from embryonic chicken neural retina contains a high mannose-type oligosaccharide that terminates with glucose linked via a phosphodiester bond to penultimate mannose. This unusual oligosaccharide seems responsible for the glycoprotein attachments to the cell-surface baseplate ligatin. Using beta-32P-UDP-3H-glucose, we demonstrate in retinal homogenates the existence of a UDP-glucose:glycoprotein glucose-1-phosphotransferase (GlcPTase) that catalyzes the synthesis of such a linkage. Characterization of the doubly labeled product resulting from activity of the transferase reveals a family of endoglycosidase H-sensitive oligosaccharides displaying a cation-exchange profile similar to that of oligosaccharides derived from ligatin-associated proteins synthesized in vivo. Further analysis confirms that the incorporation of label is due to a terminal 3H-glucose joined via a 32P-phosphodiester linkage to carbon 6 of a penultimate mannose. We propose that GlcPTase may be a controlling enzyme for the targeting of certain newly synthesized proteins to the cell surface.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Chick Embryo
  • Kinetics
  • Neurons / enzymology*
  • Oligosaccharides / biosynthesis
  • Phosphorus Radioisotopes
  • Phosphotransferases / metabolism*
  • Retina / enzymology*
  • Substrate Specificity
  • Transferases (Other Substituted Phosphate Groups)*
  • Tritium
  • Uridine Diphosphate Glucose

Substances

  • Oligosaccharides
  • Phosphorus Radioisotopes
  • Tritium
  • Phosphotransferases
  • Transferases (Other Substituted Phosphate Groups)
  • UDPglucose-glycoprotein glucose-1-phosphotransferase
  • Uridine Diphosphate Glucose