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Keywords:

  • invertebrate;
  • acetylcholine receptors;
  • physiology;
  • pharmacology;
  • Xenopus oocytes

Abstract

Three cDNAs (ALS, Dα2 and ARD) isolated from the nervous system of Drosophila and encoding putative nicotinic acetylcholine receptor subunits were expressed in Xenopus oocytes in order to study their functional properties. Functional receptors could not be reconstituted from any of these subunits taken singly or in twos and threes. In contrast, large evoked currents (in the μA range) were consistently observed upon agonist application on oocytes co-injected with ALS or Dα2 in combination with the chick β2 structural subunit. The ALS/β2 and Dα2/β2 receptors are highly sensitive to acetylcholine and nicotine, and their physiological properties resemble those of native or reconstituted receptors from vertebrates. Although the physiological properties of ALS/β2 and Dα2/β2 receptors are quite similar, clear differences appear in their pharmacological profiles. The ALS/β2 receptor is highly sensitive to α-bungarotoxin while the Dα2/β2 receptor is totally insensitive to this agent. These results demonstrate that the Drosophila ALS and Dα2 cDNAs encode neuronal nicotinic subunits responding to physiological concentrations of the agonists acetylcholine and nicotine.