title: The intracellular domain of the nicotinic acetylcholine receptor alpha subunit mediates its coclustering with rapsyn.
abstract: Muscle nicotinic acetylcholine receptors (AChRs) are immobilized at the neuromuscular junction in high-density clusters by rapsyn, a 43-kDa protein located at the cytoplasmic face of the postsynaptic membrane. When expressed in nonmuscle cells, rapsyn induces the aggregation of both assembled and unassembled AChR subunits. Here, we investigated the mechanism of rapsyn-induced clustering of the AChR alpha subunit by testing a series of alpha subunit mutants for colocalization with rapsyn patches in transfected QT6 cells. Partial or total deletion of the large intracellular domain of the alpha subunit dramatically reduced its ability to colocalize with rapsyn patches. Furthermore, insertion of the alpha subunit large intracellular domain into a potassium channel resulted in a significant increase in the channel's colocalization with rapsyn patches. We conclude that the large intracellular domain of the alpha subunit plays an important role in mediating rapsyn-induced coclustering of the AChR alpha subunit.
authors.affiliation: Department of Anatomy and Cell Biology, SUNY Health Science Center, Syracuse, New York 13210, USA.
authors.forename: M M
authors.initials: MM
authors.lastname: Maimone
authors.forename: R E
authors.initials: RE
authors.lastname: Enigk
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D002460:Cell Line; D017931:DNA Primers; D005347:Fibroblasts / Q000737:chemistry / Q000166:cytology / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D017353:Gene Deletion; D051663:Kv1.2 Potassium Channel; D009124:Muscle Proteins / Q000378:metabolism*; D016296:Mutagenesis / Q000502:physiology; D010957:Plasmids; D015221:Potassium Channels / Q000032:analysis / Q000235:genetics / Q000276:immunology; D024642:Potassium Channels, Voltage-Gated; D017434:Protein Structure, Tertiary; D011784:Quail; D011978:Receptors, Nicotinic / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000032:analysis / Q000276:immunology / Q000378:metabolism; D014162:Transfection
chemical_list: D000911:Antibodies, Monoclonal; D017931:DNA Primers; D051663:Kv1.2 Potassium Channel; D009124:Muscle Proteins; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D011978:Receptors, Nicotinic; D011993:Recombinant Fusion Proteins; C051609:peripheral membrane protein 43K