Stimulation by GDP-mannose of the biosynthesis of N-acetylglucosaminylpyrophosphoryl polyprenols by the retina.

N-Acetylglucosaminyltransferases involved in the dolichol pathway of carbohydrate activation were investigated in the retina of the embryonic chick.GDPmannose, in the presence of dolichol phosphate, caused a 10-to 16-fold stimulation in the transfer of radioactivity from UDP-C3HIGlcNAc to material extractable by chloroform/methanol (2:l).The products so affected were the "early" GlcNAc-containing lipids involved in the assembly of the core oligosaccharide of the asparagine-linked glycoproteins, identified after purification by DEAE-cellulose acetate chromatography and "LC