MGAT3

There are believed to be over 100 different glycosyltransferases involved in the synthesis of protein-bound and lipid-bound oligosaccharides. The enzyme encoded by this gene transfers a GlcNAc residue to the beta-linked mannose of the trimannosyl core of N-linked oligosaccharides and produces a bisecting GlcNAc. Multiple alternatively spliced variants, encoding the same protein, have been identified. [provided by RefSeq]

Full Name

mannosyl (beta-1,4-)-glycoprotein beta-1,4-N-acetylglucosaminyltransferase

Function

It is involved in the regulation of the biosynthesis and biological function of glycoprotein oligosaccharides. Catalyzes the addition of N-acetylglucosamine in beta 1-4 linkage to the beta-linked mannose of the trimannosyl core of N-linked sugar chains, called bisecting N-acetylglucosamine (GlcNAc). It is one of the most important enzymes involved in the regulation of the biosynthesis of glycoprotein oligosaccharides. The addition of this bisecting GlcNAc residue alters not only the composition, but also the conformation of the N-glycan. The introduction of the bisecting GlcNAc residue results in the suppression of further processing and elongation of N-glycans, precluding the formation of beta-1,6 GlcNAc branching, catalyzed by MGAT5 since it is unable to use the bisected oligosaccharide as a substrate (PubMed:19403558).

Addition of bisecting N-acetylglucosamine to CDH1/E-cadherin modulates CDH1 cell membrane location (PubMed:19403558).

Inhibits NeuAc-alpha-2,3-Gal-beta-1,4-GlcNAc- formation which modulates sialylation levels and plays a role in cell migration regulation (PubMed:26801611).

In brain, addition of bisecting N-acetylglucosamine to BACE1 blocks its lysosomal targeting in response to oxidative stress and further degradation which increases its location to early endosome and the APP cleavage (By similarity).

Biological Process

Amyloid-beta metabolic process Source: UniProtKB
Cellular response to oxidative stress Source: UniProtKB
Cognition Source: UniProtKB
N-acetylglucosamine metabolic process Source: GO_Central
Negative regulation of lysosomal protein catabolic process Source: UniProtKB
Positive regulation of protein localization to early endosome Source: UniProtKB
Protein localization Source: UniProtKB
Protein N-linked glycosylation Source: UniProtKB
Regulation of cell migration Source: UniProtKB

Cellular Location

Golgi apparatus membrane

Topology

Cytoplasmic: 1-7
Helical: 8-23
Lumenal: 24-533