Site Mapping and Characterization of O-Glycan Structures on α-Dystroglycan Isolated from Rabbit Skeletal Muscle

• DOI: 10.1074/jbc.m110.126474
• Publication Date: 2010-05-28T01:39:53Z
• Authors: Stephanie H. Stal...; Sana Hashmi; Jae-Min Lim; Kazuhiro Aoki; Mindy Porterfield; Gerardo Gutierrez...; James Wheeler; James M. Ervasti; Carl Bergmann; Michael Tiemeyer; Lance Wells
• Keywords: Glycomics; Dystroglycan

The main extracellular matrix binding component of the dystrophin-glycoprotein complex, α-dystroglycan (α-DG), which was originally isolated from rabbit skeletal muscle, is an extensively O-glycosylated protein. Previous studies have shown α-DG to be modified by both O-GalNAc- and O-mannose-initiated glycan structures. O-Mannosylation, accounts for up 30% reported O-linked structures in certain tissues, has been rarely observed on mammalian proteins. Mutations multiple genes encoding defined or putative glycosyltransferases involved O-mannosylation are causal various forms congenital muscular dystrophy. Here, we explore glycosylation purified muscle detail. Using tandem mass spectrometry approaches, identify 4 17 O-GalNAc-initiated muscle. Additionally, demonstrate use spectrometry-based workflows directly analyze glycopeptides generated By combining glycomics analysis 91 α-DG, were able assign 21 different residues as being O-glycosylation with differing degrees microheterogeneity; 9 sites 14 O-GalNAcylation only two definitively exhibiting occupancy either type glycan. distribution identified suggests a limited role local primary sequence dictating attachment.