alpha-1,3-mannosyl-glycoprotein 4-beta-N-acetylglucosaminyltransferase A; UDP-N-acetylglucosamine: alpha-1,3-D-mannoside beta-1,4-N-acetylglucosaminyltransferase IVa; N-glycosyl-oligosaccharide-glycoprotein N-acetylglucosaminyltransferase IVa; N-acetylglucosaminyltransferase IVa, GnT-IVa, GlcNAc-T IVa, [contains: alpha-1,3-mannosyl-glycoprotein 4-beta-N-acetylglucosaminyltransferase A soluble form] (MGAT4A)

Function

• glycosyltransferase, glycosylation pathway
• role in transfer of N-acetylglucosamine (GlcNAc) to the core mannose residues of N-linked glycans
• atalyzes the formation of GlcNAcbeta1-4 branch on GlcNAcbeta1-2Manalpha1-3 arm of the core structure of N-linked glycans
• required for production of tri- & tetra-antennary N-linked sugar chains
• role in glucose transport by mediating SLC2A2/GLUT2 glycosylation, thus controlling cell-surface expression of SLC2A2 in pancreatic beta cells

UDP-N-acetyl-D-glucosamine
          +
3-(2-(N-acetyl-beta-D-glucosaminyl)-alpha-D-mannosyl)-beta-D-
mannosyl-R
       <-->
        UDP
          +
3-(2,4-bis(N-acetyl-beta-D-glucosaminyl)-alpha-D-mannosyl)-beta-D-
mannosyl-R

Cofactor: divalent metal cations

Kinetic parameters:

• KM=0.118 mM for UDP-GlcNAc

Structure

belongs to the glycosyltransferase 54 family

Compartment

• Golgi membrane, secreted
• membrane & processed soluble form

Expression

• expressed in pancreas, spleen, thymus, prostate, small intestine, peripheral blood leukocytes, lymph node

Pathology

• strongly overexpressed in choriocarcinoma cancer cell lines
• down-regulated in pancreatic cancer

More general terms

• UDP-N-acetylglucosamine:alpha-1,3-D-mannoside beta-1,4-N-acetylglucosaminultransferase

Database

• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=11320
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:11320
• OMIM: https://mirror.omim.org/entry/604623
• UniProt: http://www.uniprot.org/uniprot/Q9UM21.html