A cAMP-dependent Ca2+ signalling pathway at the endplate provided by the γ to ε subunit switch in ACh receptors
Abstract During development of neuromuscular junctions there is a switch in the expression of acetylcholine receptors (AChR) from an embryonic form (γ-AChR) to an adult form (e-AChR). Studies with γ- and e-AChRs expressed in Xenopus oocytes showed that the γ to e subunit switch accelerates rates of desensitization and increases Ca 2+ permeability. Site-directed mutagenesis of the γ and e subunits suggests that these changes are regulated by cAMP-dependent phosphorylation on the e subunit. These results suggest that the γ to e subunit switch could provide for a cAMP- dependent Ca 2+ signalling pathway at the endplate.