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Nicotinic acetylcholine receptor chimeras of rat alpha 7 and Drosophila SAD reveal species-specific agonist binding regions

Beukel, I.V.n-Den; Klaassen, R.S.it, G.; Kleef, R.; Oortgiesen, M.

Pesticide science 55(10): 1031-1033

1999


Accession: 003212897

Species-specific agonist binding regions of nicotinic acetylcholine receptors (nAChR) were examined. Imidacloprid and physostigmine (Phy) selectivity activated insect nAChR composed of Drosophila second alpha-like subunit (SAD) and chick beta2, in contrast to rat alpha7 nAChR. The Phyactivated currents were alpha-bungarotoxin (alpha-BGT) sensitive, suggesting activation at the agonist binding loops. Several SADalpha-7 chimeras were constructed, by switching agonist binding regions, and expressed in oocytes. Though none of the chimeras was activated by a range of nicotinic agonists, [125I]alpha-BGT binding revealed homomeric assembly of all chimeric cDNAs. Phy differentially displaced [125I]alpha-BGT from the nAChR chimeras, suggesting that the beta subunit is not involved in Phy binding, and that Phy targets the insect agonist binding loop C.

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