CLONING AND FUNCTIONAL-CHARACTERIZATION OF 2 NOVEL NICOTINIC ACETYLCHOLINE-RECEPTOR ALPHA-SUBUNITS FROM THE INSECT PEST MYZUS-PERSICAE

Nicotinic acetylcholine receptors play a major role in excitatory neur otransmission in insect CNSs and constitute an important target for in secticides. Here, we report the isolation and functional characterisat ion of two cDNAs encoding nicotinic acetylcholine receptor alpha subun its from a major insect pest, the peach-potato aphid Myzus persicae. T hese two subunits, termed Mp alpha 1 and Mp alpha 2, are respective st ructural homologues of the Drosophila D alpha 2/Schistocerca gregaria alpha L1 alpha-subunit pair and the Drosophila ALS alpha subunit. Xeno pus oocyte expression confirmed that each Myzus subunit can form funct ional acetylcholine- or nicotine-gated channels. However, some electro physiological and pharmacological properties of the Myzus subunits wer e distinct from those encoded by the corresponding Drosophila subunits , Coexpression of the Myzus subunits with the chick beta 2 subunit rev ealed other differences from the Drosophila system, as only very limit ed potentiation of agonist-induced currents was observed with Mp alpha 2 and none with Mp alpha 1. Available data therefore indicate that st ructurally homologous insect nicotinic acetylcholine receptor alpha su bunits from different species can exhibit distinctive physiological an d pharmacological characteristics.