Alpha-1,6-mannosylglycoprotein 6-beta-N-acetylglucosaminyltransferase B (MGAT5B)

Alpha-1,6-mannosylglycoprotein 6-beta-N-acetylglucosaminyltransferase B (MGAT5B, also known as GnT-IX or GnT-Vb) is a glycosyltransferase enzyme primarily expressed in the brain that adds a β1-6-linked N-acetylglucosamine residue to mannose within O- and N-linked glycan cores. This unique branching activity is critical for the production of 2,6-branched structures in brain O-mannosyl glycans, influencing neuronal cell adhesion, migration, and certain membrane protein functions. MGAT5B is closely related to MGAT5 (GnT-V), which is prominent in cancer biology, but MGAT5B shows restricted, brain-specific expression and is essential for maintaining proper glycosylation processes implicated in neuromuscular disorders and glycosylation diseases. The presence and activity of MGAT5B may affect cellular phenotypes in the nervous system and can modulate disease progression associated with glycan alterations. Currently, MGAT5B serves as a molecular marker in research but has no direct clinical targeting agents or established utility as a therapeutic or diagnostic biomarker.

Other names

GnT-IXGnT-VbGlcNAc-T VbhGnTVbKIAA2008FLJ25132GNT-IXGNT-VBAlpha-mannoside beta-1,6-N-acetylglucosaminyltransferase BMannoside acetylglucosaminyltransferase 5BN-acetylglucosaminyltransferase IXN-acetylglucosaminyl-transferase Vb

No mechanism of action reported for direct MGAT5B inhibitors. By analogy to MGAT5, inhibition would block the transfer of β1-6-linked N-acetylglucosamine (GlcNAc) to mannose, affecting glycan branching and cell-cell adhesion, possibly reducing cancer cell migration/metastasis.