A cAMP-dependent Ca2+ signalling pathway at the endplate provided by the gamma to epsilon subunit switch in ACh receptors.
During development of neuromuscular junctions there is a switch in the expression of acetylcholine receptors (AChR) from an embryonic form (gamma-AChR) to an adult form (epsilon-AChR). Studies with gamma- and epsilon-AChRs expressed in Xenopus oocytes showed that the gamma to epsilon subunit switch accelerates rates of desensitization and increases Ca2+ permeability. Site-directed mutagenesis of the gamma and epsilon subunits suggests that these changes are regulated by cAMP-dependent phosphorylation on the epsilon subunit. These results suggest that the gamma to epsilon subunit switch could provide for a cAMP-dependent Ca2+ signalling pathway at the endplate.
Department of Psychobiology, University of California, Irvine 92717-4550.
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Nishizaki
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Sumikawa
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001483:Base Sequence; D002118:Calcium / Q000502:physiology*; D000242:Cyclic AMP / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D004625:Embryo, Nonmammalian; D005071:Evoked Potentials / Q000187:drug effects; D005260:Female; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D009045:Motor Endplate / Q000187:drug effects / Q000502:physiology*; D016297:Mutagenesis, Site-Directed; D009838:Oligodeoxyribonucleotides; D009865:Oocytes / Q000187:drug effects / Q000502:physiology; D011950:Receptors, Cholinergic / Q000096:biosynthesis* / Q000737:chemistry; D015398:Signal Transduction; D014981:Xenopus
D046911:Macromolecular Substances; D009838:Oligodeoxyribonucleotides; D011950:Receptors, Cholinergic; D004533:Egtazic Acid; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; D000109:Acetylcholine; D002118:Calcium