SYNTHESIS OF CAT MUSCLE ACETYLCHOLINE RECEPTORS BY XENOPUS OOCYTES

Messenger RNA (mRNA) extracted from innervated or denervated cat muscles was injected into Xenopus oocytes.mRNA from both types of muscle directed the synthesis of acetylcholine (ACh) receptors, which became incorporated into the oocyte membrane.Activation of these receptors by ACh produced an inward current at membrane potentials more negative than --10 mV.The equilibrium potential for ACh action was approximately the same in oocytes injected with either denervated or innervated muscle mRNA.In contrast to the oocytes own muscarinic receptors, the new ACh-receptors could be blocked by ot-bungarotoxin and dtubocurarine, but were not blocked by atropine.Intracellular application of ACh did not activate the receptors, indicating that most of them were inserted in the membrane with their ACh recognition site exposed to the external medium.