PglA and PglH compete for substrates generated by PglB/PglB2 in a branched pathway for protein glycan biosynthesis. (A) PglH is involved in the broad-spectrum O-linked glycosylation systems in Neisseria by adding glucose onto diNacBac or GATDH UndPP monosaccharide. (B) The figure displays the chemical reactions of the phospho-glycosyltransferases, PglB/PglB2, and the glycosyltransferases, PglA and PglH. Boxed are the substrates (R) for the two glycosyltransferases, PglB and PglB2, and side groups (R′) on the glycans. Und, undecaprenol; UDP, uridine diphosphate.