Phosphorylation in vitro of Membrane Fragments from Torpedo marmorata Electric Organ

摘要: Acetylcholine receptor-rich membrane fragments purified from Torpedo inarmorata electric organ were phosphorylated, in vitro, by endogenous protein kinases. The 40000-Mr chain, which carries the acetylcholine receptor site, was never labelled; on other hand, bands of apparent molecular weights 43 000,50000 and 66000, are present membranes, repeatedly phosphorylated. phosphorylation these three peptides required presence divalent cations, such as MgZf or Mn2+, was, addition, stimulated up to 3-5-fold K'. effect Na' ions appeared less specific since reduced labelling all polypeptides susceptible phosphorylation. Cholinergic agonists antagonists, local anesthetics cyclic nucleotides did not affect membranes. Phosphorylation selectively modified solubilization several nondenaturing detergents : phosphorylated 000-M,, 50 000-M, 66 solubilized at lower concentrations detergent than their non-phosphorylated counterparts. Two-dimensional gels revealed existence a charge heterogeneity 40 000-MI 43000-M, chains. microheterogeneity 43000-MI but that 40000-M, might result selective this particular chain.