MGAT3
Description
The MGAT3 (beta-1,4-mannosyl-glycoprotein 4-beta-N-acetylglucosaminyltransferase) is a protein-coding gene located on chromosome 22.
MGAT3 is a human gene encoding the enzyme beta-1,4-mannosyl-glycoprotein 4-beta-N-acetylglucosaminyltransferase. This enzyme is one of over 100 glycosyltransferases involved in the synthesis of protein-bound and lipid-bound oligosaccharides. MGAT3 adds a GlcNAc residue to the beta-linked mannose of the trimannosyl core of N-linked oligosaccharides, creating a bisecting GlcNAc. Multiple alternatively spliced variants of the MGAT3 gene have been identified, all encoding the same protein.
MGAT3 plays a key role in regulating the biosynthesis and function of glycoprotein oligosaccharides. It adds a bisecting N-acetylglucosamine (GlcNAc) residue to the trimannosyl core of N-linked sugar chains, modifying both the composition and conformation of the N-glycan. This addition inhibits further processing and branching of N-glycans, preventing the formation of beta-1,6 GlcNAc branching catalyzed by MGAT5. MGAT3's activity influences cell migration by modulating sialylation levels and affecting the cell membrane location of proteins like CDH1/E-cadherin. In brain, MGAT3 adds bisecting GlcNAc to BACE1, blocking its lysosomal targeting and increasing its localization to the early endosome, leading to enhanced APP cleavage. MGAT3 interacts with MGAT4D.
MGAT3 is also known as GNT-III, GNT3.
