Differential Vicia villosa agglutinin reactivity identifies three distinct dystroglycan complexes in skeletal muscle

J Biol Chem. 2001 Sep 14;276(37):35078-86. doi: 10.1074/jbc.M103843200. Epub 2001 Jul 17.

Abstract

We present evidence for the expression of three alpha-dystroglycan glycoforms in skeletal muscle cells, including two minor glycoforms marked by either patent or latent reactivity with the N-acetylgalactosamine-specific lectin Vicia villosa agglutinin. Both minor glycoforms co-isolated with beta-dystroglycan, but not with other dystrophin/utrophin-glycoprotein complex components, suggesting that they may perform distinct or modified cellular functions. We also confirmed that both patent and latent V. villosa agglutinin-reactive alpha-dystroglycan glycoforms are expressed in C2C12 myotubes. However, we found that the combined effect of saturating concentrations of V. villosa agglutinin and laminin-1 were strictly additive with respect to acetylcholine receptor cluster formation in C2C12 myotubes, which suggests that laminin-1 and V. villosa agglutinin do not compete for the same binding site on the cell surface. Finally, although beta-N-acetylhexosaminidase digestion dramatically inhibited agrin-, V. villosa agglutinin-, and laminin-1-induced acetylcholine receptor clustering in C2C12 myotubes, treatment with this enzyme had no effect on the amount of alpha-dystroglycan that was bound to V. villosa agglutinin-agarose. We conclude that alpha-dystroglycan is not the V. villosa agglutinin receptor implicated in acetylcholine receptor cluster formation. However, our data provide new support for the hypothesis that different glycoforms of alpha-dystroglycan may perform distinct functions even within the same cell.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Cell Line
  • Cytoskeletal Proteins / analysis*
  • Cytoskeletal Proteins / physiology
  • Dystroglycans
  • Laminin / pharmacology
  • Lectins / metabolism*
  • Lectins / pharmacology
  • Membrane Glycoproteins / analysis*
  • Membrane Glycoproteins / physiology
  • Muscle, Skeletal / chemistry*
  • Neuraminidase / pharmacology
  • Neuromuscular Junction / chemistry
  • Plant Lectins*
  • Rabbits
  • Receptors, Cholinergic / drug effects
  • beta-N-Acetylhexosaminidases / pharmacology

Substances

  • Cytoskeletal Proteins
  • Laminin
  • Lectins
  • Membrane Glycoproteins
  • Plant Lectins
  • Receptors, Cholinergic
  • Vicia lectins
  • laminin 1
  • Dystroglycans
  • Neuraminidase
  • beta-N-Acetylhexosaminidases