PMID: 20507882

 

    Legend: Sugar

Title : Characterization of site-specific O-glycan structures within the mucin-like domain of alpha-dystroglycan from human skeletal muscle

Abstract :

1. The glycosylation of the extracellular protein alpha-dystroglycan is important for its ligand-binding activity, and altered or blocked glycosylation is associated with several forms of congenital muscular dystrophies
2. By immunoprecipitation and sialic acid capture-and-release enrichment strategies, we isolated tryptic glycopeptides of alpha-dystroglycan from human skeletal muscle
3. Nano-liquid chromatography tandem mass spectrometry was used to identify both glycopeptides and peptides corresponding to the mucin-like and C-terminal domain of alpha-dystroglycan
4. The O-glycans found had either Hex-O-Thr or HexNAc-O-Ser/Thr Thr or HexNAc-O-Ser/Thr anchored structures, which were often elongated and frequently, but not always, terminated with sialic acid.
5. The HexNAc-O-Ser/Thr, but not Hex-O- Thr glycopeptides , displayed heterogeneity regarding glycan core structures and level of glycosylation site occupancy
6. We demonstrate for the first time glycan attachment sites of the NeuAcHexHexNAcHex-O structure corresponding to the anticipated Neu5Acalpha3Galbeta4GlcNAcbeta2Man-O-glycan (sLacNAc-Man), within the mucin-like domain of human alpha-dystroglycan from human skeletal muscle
7. Twenty-five glycopeptides were characterized from human alpha-dystroglycan , which provide insight to the complex in vivo O-glycosylation of alpha-dystroglycan