title: The effects of post-translational processing on dystroglycan synthesis and trafficking.
abstract: Dystroglycan is a component of the dystrophin glycoprotein complex that is cleaved into two polypeptides by an unidentified protease. To determine the role of post-translational processing on dystroglycan synthesis and trafficking we expressed the dystroglycan precursor and mutants thereof in a heterologous system. A point mutant in the processing site, S655A, prevented proteolytic cleavage but had no effect upon the surface localisation of dystroglycan. Mutation of two N-linked glycosylation sites that flank the cleavage site inhibited proteolytic processing of the precursor. Furthermore, chemical inhibition of N- and O-linked glycosylation interfered with the processing of the precursor and reduced the levels of dystroglycan at the cell surface. Dystroglycan processing was also inhibited by the proteasome inhibitor lactacystin. N-linked glycosylation is a prerequisite for efficient proteolytic processing and cleavage and glycosylation are dispensable for cell surface targeting of dystroglycan.
authors.affiliation: Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK.
authors.forename: Chris T
authors.initials: CT
authors.lastname: Esapa
authors.forename: Graham R B
authors.initials: GR
authors.lastname: Bentham
authors.forename: Jörn E
authors.initials: JE
authors.lastname: Schröder
authors.forename: Stephan
authors.initials: S
authors.lastname: Kröger
authors.forename: Derek J
authors.initials: DJ
authors.lastname: Blake
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D001692:Biological Transport; D016466:CHO Cells; D019556:COS Cells; D002460:Cell Line; D002645:Chickens; D002522:Chlorocebus aethiops; D006224:Cricetinae; D003598:Cytoskeletal Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D049030:Dystroglycans; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006031:Glycosylation / Q000187:drug effects; D008562:Membrane Glycoproteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D017354:Point Mutation; D011498:Protein Precursors / Q000235:genetics / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D016415:Sequence Alignment; D014162:Transfection
chemical_list: D003598:Cytoskeletal Proteins; D004791:Enzyme Inhibitors; D008562:Membrane Glycoproteins; D011498:Protein Precursors; D049030:Dystroglycans