Schulz R, Sawruk E, Mülhardt C, Bertrand S, Baumann A, Phannavong B, Betz H, Bertrand D, Gundelfinger E D, Schmitt B
Leibniz Institute for Neurobiology, Magdeburg, Germany.
J Neurochem. 1998 Aug;71(2):853-62. doi: 10.1046/j.1471-4159.1998.71020853.x.
Nicotinic acetylcholine (ACh) receptors (nAChRs) are important excitatory neurotransmitter receptors in the insect CNS. We have isolated and characterized the gene and the cDNA of a new nAChR subunit from Drosophila. The predicted mature nAChR protein consists of 773 amino acid residues and has the structural features of an ACh-binding alpha subunit. It was therefore named D alpha3, for Drosophila alpha-subunit 3. The d alpha3 gene maps to the X chromosome at position 7E. The properties of the D alpha3 protein were assessed by expression in Xenopus oocytes. D alpha3 did not form functional receptors on its own or in combination with any Drosophila beta-type nAChR subunit. Nondesensitizing ACh-evoked inward currents were observed when D alpha3 was coexpressed with the chick beta2 subunit. Half-maximal responses were at approximately 0.15 microM ACh with a Hill coefficient of approximately 1.5. The snake venom component alpha-bungarotoxin (100 nM) efficiently but reversibly blocked D alpha3/beta2 receptors, suggesting that D alpha3 may be a component of one of the previously described two classes of toxin binding sites in the Drosophila CNS.
烟碱型乙酰胆碱（ACh）受体（nAChRs）是昆虫中枢神经系统中重要的兴奋性神经递质受体。我们已从果蝇中分离并鉴定了一种新的nAChR亚基的基因和cDNA。预测的成熟nAChR蛋白由773个氨基酸残基组成，具有ACh结合α亚基的结构特征。因此，它被命名为Dα3，即果蝇α亚基3。dα3基因定位于X染色体上的7E位置。通过在非洲爪蟾卵母细胞中表达来评估Dα3蛋白的特性。Dα3单独或与任何果蝇β型nAChR亚基组合时都不能形成功能性受体。当Dα3与鸡β2亚基共表达时，观察到了不脱敏的ACh诱发内向电流。半数最大反应出现在约0.15μM ACh处，希尔系数约为1.5。蛇毒成分α-银环蛇毒素（100 nM）能有效但可逆地阻断Dα3/β2受体，这表明Dα3可能是果蝇中枢神经系统中先前描述的两类毒素结合位点之一的组成部分。
