Phosphorylation of the α1,2-linked mannosylsaccharide by N-acetylglucosamine-1-phosphotransferase from fibroblasts occurs at the terminal mannose

UDP-GlcNAc: Lysosomal enzyme precursor N-acetylglucosamine-1-phosphotransferase activity from normal fibroblasts was measured using methyl 2-0-(α-D-mannopyranosyl)6-deoxy-6-fluoro-α-D-mannopyranoside and methyl 2-0-(6-deoxy-6-fluoro-α-D-mannopyranosyl)α-D-mannopyranoside as acceptors. The results indicate that the phosphorylation in man α 1→2 man sequence occurs at the C-6 position of the terminal mannose residue.