Regulatory Mechanisms of Laminin-Binding O-Mannosyl Glycan Biosynthesis

Abstract

The plasma membrane-localized protein α-dystroglycan (α-DG) is modified by the core M3-type glycan, a characteristic O-mannosyl glycan, on particular Thr residues. Defects in the core M3-type glycan synthesis cause a group of congenital muscular dystrophies with neuronal abnormalities. In 2016, the complete structure of the core M3-type glycan was clarified and ribitol phosphate (RboP) or glycerol phosphate (GroP) were identified as novel glycan constituents in mammals. However, the mechanisms that regulate the biosynthesis of this unique glycan remain unclear. This review summarizes our recent progress in understanding the regulatory mechanisms of core M3-type glycan biosynthesis, with a special focus on the molecular machinery of RboP and GroP modifications.