title: Biosynthesis of dystroglycan: processing of a precursor propeptide.
abstract: Dystroglycan is a cytoskeleton-linked extracellular matrix receptor expressed in many cell types. Dystroglycan is composed of alpha- and beta-subunits which are encoded by a single mRNA. Using a heterologous mammalian expression system, we provide the first biochemical evidence of the alpha/beta-dystroglycan precursor propeptide prior to enzymatic cleavage. This 160 kDa dystroglycan propeptide is processed into alpha- and beta-dystroglycan (120 kDa and 43 kDa, respectively). We also demonstrate that the precursor propeptide is glycosylated and that blockade of asparagine-linked (N-linked) glycosylation did not prevent the cleavage of the dystroglycan precursor peptide. However, inhibition of N-linked glycosylation results in aberrant trafficking of the alpha- and beta-dystroglycan subunits to the plasma membrane. Thus, dystroglycan is synthesized as a precursor propeptide that is post-translationally cleaved and differentially glycosylated to yield alpha- and beta-dystroglycan.
authors.affiliation: Department of Physiology, Howard Hughes Medical Institute, University of Iowa College of Medicine, Iowa City, IA, USA.
authors.forename: K H
authors.initials: KH
authors.lastname: Holt
authors.forename: R H
authors.initials: RH
authors.lastname: Crosbie
authors.forename: D P
authors.initials: DP
authors.lastname: Venzke
authors.forename: K P
authors.initials: KP
authors.lastname: Campbell
mesh_terms: D000581:Amidohydrolases / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D002462:Cell Membrane / Q000378:metabolism; D006224:Cricetinae; D017077:Culture Media, Conditioned / Q000378:metabolism; D003587:Cytomegalovirus / Q000235:genetics; D003598:Cytoskeletal Proteins / Q000096:biosynthesis* / Q000235:genetics; D049030:Dystroglycans; D004591:Electrophoresis, Polyacrylamide Gel; D005822:Genetic Vectors; D006031:Glycosylation; D015151:Immunoblotting; D008562:Membrane Glycoproteins / Q000096:biosynthesis* / Q000235:genetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009844:Oligosaccharides / Q000378:metabolism; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase; D010455:Peptides / Q000378:metabolism*; D011498:Protein Precursors / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D012333:RNA, Messenger / Q000378:metabolism; D011817:Rabbits; D014162:Transfection; D014415:Tunicamycin / Q000378:metabolism
chemical_list: D017077:Culture Media, Conditioned; D003598:Cytoskeletal Proteins; D008562:Membrane Glycoproteins; D009844:Oligosaccharides; D010455:Peptides; D011498:Protein Precursors; D012333:RNA, Messenger; D014415:Tunicamycin; D049030:Dystroglycans; D000581:Amidohydrolases; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase