Matriglycan biosynthesis on DAG1

α-Dystroglycan is a 624 aa product of the dystroglycan (DAG1) gene. As a monomer or a heterodimer with the 324 aa beta-dystroglycan it is a central component of the dystrophin-glycoprotein complex. Most of its properties like laminin binding or arenavirus receptor function (reviewed in Moriguchi & Campbell, 2015; Nickolls & Bönnemann, 2018; Katz & Diskin, 2024) are provided by matriglycan chains that are biosynthesized on threonine residues, in the mucin like domain, positions 317 455, of α-dystroglycan. Matriglycan is a glycosaminoglycan (GAG)-like polysaccharide consisting of a long linear chain of repeating [-3GlcAβ1,3Xylα1-] heterodisaccharide and two ribitolphosphate subunits connected via the trisaccharide linker GalNAc-GlcNAc-ManP (aka Core M3) to O-threonines on α-dystroglycan. At least 19 genes are involved in the biosynthesis of this modification, mutations of which have been shown to lead to α-dystroglycanopathies, rare illnesses ranging from mild muscular dystrophy to severe congenital syndromes that are characterized by progressive muscle weakness, brain abnormalities and seizures, as well as eye problems.

Summary from Reactome (R-HSA-9939291), read 2026-09-23.