Glycosyltransferase involved in the biosynthesis of neomycin by mediating glycosylation of ribostamycin with UDP-GlcNAc as a sugar donor to generate 2'''-acetyl-6'''-hydroxyneomycin C. ribostamycin + UDP-N-acetyl-alpha-D-glucosamine = 2'''-acetyl-6'''-hydroxyneomycin C + H(+) + UDP Antibiotic biosynthesis; neomycin biosynthesis. Belongs to the glycosyltransferase group 1 family. Glycosyltransferase 4 subfamily.