Of a part of the type 1 LacNAc (Gal -1,3-GlcNAc) and type 2 LacNAc (Gal -1,4-GlcNAc) structures that build the scaffold for blood group H and Lewis-type units (58). Some human pathogens use the GlcNAc residue as a binding receptor; e.g., the fimbrial adhesin F17-G of enterotoxigenic E. coli binds to N-acetylglucosamine-presenting receptors on the microvilli of the intestinal epithelium of ruminant