FIGURE 1.

Core O-Man structures on α-dystroglycan. A, POMGNT1 is responsible for generating the M1 core glycan structure that can be branched by MGAT5B to generate the M2 core, whereas POMGNT2 is responsible for generating the M3 core glycan structure. B, schematic of known O-mannosylated sites on α-dystroglycan addressed in this study. Thr-317 and Thr-379 are elaborated with the M3 core glycan structure, whereas Thr-341 and Thr-414 are elaborated with M1 core glycan structures that can be further elaborated to core M2 glycan structures. Glycan symbols follow guidelines outlined in Ref. 38. SP, signal peptide.