Synonyms:HEXC, KIAA0679, MEA5 Background:Isoform 1: Cleaves GlcNAc but not GalNAc from O-glycosylated proteins. Can use p-nitrophenyl-beta-GlcNAc and 4-methylumbelliferone-GlcNAc as substrates but not p-nitrophenyl-beta-GalNAc or p-nitrophenyl-alpha-GlcNAc(in vitro)(PubMed:11148210). Does not bind acetyl-CoA and does not have histone acetyltransferase activity(PubMed:24088714). Isoform 3: Cleaves GlcNAc but not GalNAc from O-glycosylated proteins. Can use p-nitrophenyl-beta-GlcNAc as substrate but not p-nitrophenyl-beta-GalNAc or p-nitrophenyl-alpha-GlcNAc(in vitro), but has about six times lower specific activity than isoform 1.