External links. Alpha-1,3-mannosyl-glycoprotein+2-beta-N-acetylglucosaminyltransferase at the US National Library of Medicine Medical Subject Headings (MeSH). Alpha-1,3-mannosyl-glycoprotein 4-beta-N-acetylglucosaminyltransferase A is a type II membrane protein and an enzyme – particularly a glycosyltransferase – that, in addition to the related isoenzyme B , takes part in the transfer of N-acetylglucosamine (GlcNAc) to the core mannose residues of N-linked glycans in Golgi apparatus.. Protein target information for Alpha-1,3-mannosyl-glycoprotein 2-beta-N-acetylglucosaminyltransferase (human). Find diseases associated with this biological target and compounds tested against it in bioassay experiments.. acetylglucosaminyltransferase activity / alpha-1,3-mannosylglycoprotein 2-beta-N-acetylglucosaminyltransferase activity / metal ion binding Processes carbohydrate metabolic process / cellular protein metabolic process / in utero embryonic development / post-translational protein modification / protein glycosylation / protein N-linked glycosylation via asparagine / UDP-N-acetylglucosamine . Mannosyl (alpha-1,3-)-glycoprotein beta-1,2-N-acetylglucosaminyltransferase I (MGAT1), originally termed N-acetylglucosaminyltransferase I, abbreviated GlcNAc-TI, was the first N-glycan branching GlcNAc-transferase for which an assay was developed (Gottlieb et al. 1975; Stanley et al. 1975).. Alpha-1,3-mannosyl-glycoprotein 4-beta-N-acetylglucosaminyltransferase B (EC: 188.8.131.52 Search proteins in UniProtKB for this EC number. See the description of this EC number in ENZYME..