title: Evidence for in situ and in vitro association between beta-dystroglycan and the subsynaptic 43K rapsyn protein. Consequence for acetylcholine receptor clustering at the synapse.
abstract: The accumulation of dystrophin and associated proteins at the postsynaptic membrane of the neuromuscular junction and their co-distribution with nicotinic acetylcholine receptor (AChR) clusters in vitro suggested a role for the dystrophin complex in synaptogenesis. Co-transfection experiments in which alpha- and beta-dystroglycan form a complex with AChR and rapsyn, a peripheral protein required for AChR clustering (Apel, D. A., Roberds, S. L., Campbell, K. P., and Merlie, J. P. (1995) Neuron 15, 115-126), suggested that rapsyn functions as a link between AChR and the dystrophin complex. We have investigated the interaction between rapsyn and beta-dystroglycan in Torpedo AChR-rich membranes using in situ and in vitro approaches. Cross-linking experiments were carried out to study the topography of postsynaptic membrane polypeptides. A cross-linked product of 90 kDa was labeled by antibodies to rapsyn and beta-dystroglycan; this demonstrates that these polypeptides are in close proximity to one another. Affinity chromatography experiments and ligand blot assays using rapsyn solubilized from Torpedo AChR-rich membranes and constructs containing beta-dystroglycan C-terminal fragments show that a rapsyn-binding site is present in the juxtamembranous region of the cytoplasmic tail of beta-dystroglycan. These data point out that rapsyn and dystroglycan interact in the postsynaptic membrane and thus reinforce the notion that dystroglycan could be involved in synaptogenesis.
authors.affiliation: Biologie Cellulaire des Membranes, Département de Biologie Supramoléculaire et Cellulaire, Institut Jacques Monod, UMR 9922, CNRS et Université Paris VII, 2 Place Jussieu, 75251 Paris Cédex 05, France.
authors.forename: A
authors.initials: A
authors.lastname: Cartaud
authors.forename: S
authors.initials: S
authors.lastname: Coutant
authors.forename: T C
authors.initials: TC
authors.lastname: Petrucci
authors.forename: J
authors.initials: J
authors.lastname: Cartaud
mesh_terms: D000818:Animals; D003432:Cross-Linking Reagents / Q000737:chemistry; D003593:Cytoplasm / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000737:chemistry / Q000378:metabolism*; D049030:Dystroglycans; D005982:Glutathione Transferase / Q000737:chemistry; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000378:metabolism*; D009124:Muscle Proteins / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D011950:Receptors, Cholinergic / Q000378:metabolism*; D011978:Receptors, Nicotinic / Q000737:chemistry / Q000378:metabolism*; D013388:Succinimides / Q000737:chemistry; D013569:Synapses / Q000378:metabolism*; D014101:Torpedo
chemical_list: D003432:Cross-Linking Reagents; D003598:Cytoskeletal Proteins; D008562:Membrane Glycoproteins; D009124:Muscle Proteins; D011950:Receptors, Cholinergic; D011978:Receptors, Nicotinic; D013388:Succinimides; C051609:peripheral membrane protein 43K; D049030:Dystroglycans; C042424:succinimidyl 4-(4-maleimidophenyl)butyrate; D005982:Glutathione Transferase