Existence of two acetylcholinesterases in the mosquito Culex pipiens (Diptera: Culicidae)
Existence of two acetylcholinesterases in the mosquito Culex pipiens (Diptera: Culicidae)
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DOI：
10.1046/j.1471-4159.1996.67052115.x
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发表时间：
1996-11-01
影响因子：
4.7
通讯作者：
Arpagaus, M
中科院分区：
文献类型：
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作者：
Bourguet, D;Raymond, M;Arpagaus, M
两种乙酰胆碱酯酶 (AChE)，即 AChE1 和 AChE2，在底物特异性和抑制剂敏感性的某些方面有所不同，已在淡色库蚊中进行了表征。蔗糖梯度超速离心和AChE活性峰组分的非变性凝胶电泳的结果表明，每个ACRE以两种分子形式存在：一种具有糖脂锚的两亲性二聚体和一种不与非变性去污剂相互作用的亲水性二聚体。磷脂酰肌醇特异性磷脂酶 C 处理可将每种类型的两亲性二聚体转化为相应的亲水性二聚体。分子形式的 AChE1 的电泳迁移率比 AChE2 的分子形式低。然而，两亲二聚体和亲水二聚体具有相似的沉降系数（分别为5.5S和6.5S）。 AChE1 和 AChE2 二聚体（两亲性或亲水性）在允许果蝇 AChE 二聚体还原的条件下抵抗二硫苏糖醇还原。在对杀虫剂敏感的菌株S-LAB中，AChE1被5 x 10(-4) M残杀威（一种氨基甲酸酯杀虫剂）抑制，而AChE2具有抗性。所有动物都会被这个浓度的残杀威杀死，这表明只有 AChE1 能够实现突触处神经递质水解的生理功能。在抗杀虫剂菌株 MSE 中，接触 5 x 10(-4) M 残杀威后没有死亡：AChE2 对残杀威的敏感性不变，而 AChE1 现在对 5 x 10(-4) M 残杀威具有抗性。我们讨论了 AChE1 和 AChE2 是单个基因的组织特异性翻译后修饰产物的可能性，但我们建议，根据最近在蚊子分子水平上获得的结果，它们是由两个不同的基因编码的。
Two acetylcholinesterases (AChEs), AChE1 and AChE2, differing in substrate specificity and in some aspects of inhibitor sensitivity, have been characterized in the mosquito Culex pipiens. The results of ultracentrifugation in sucrose gradients and nondenaturing gel electrophoresis of AChE activity peak fractions show that each ACRE is present as two molecular forms: one amphiphilic dimer possessing a glycolipid anchor and one hydrophilic dimer that does not interact with nondenaturing detergents. Treatment by phosphatidylinositol-specific phospholipase C converts each type of amphiphilic dimer into the corresponding hydrophilic dimer. Molecular forms of AChE1 have a lower electrophoretic mobility than those of AChE2. However, amphiphilic dimers and hydrophilic dimers have similar sedimentation coefficients (5.5S and 6.5S, respectively). AChE1 and AChE2 dimers, amphiphilic or hydrophilic, resist dithiothreitol reduction under conditions that allow reduction of Drosophila AChE dimers. In the insecticide-susceptible strain S-LAB, AChE1 is inhibited by 5 x 10(-4) M propoxur (a carbamate insecticide), whereas AChE2 is resistant. All animals are killed by this concentration of propoxur, indicating that only AChE1 fulfills the physiological function of neurotransmitter hydrolysis at synapses. In the insecticide-resistant strain, MSE, there is no mortality after exposure to 5 x 10(-4) M propoxur: AChE2 sensitivity to propoxur is unchanged, whereas AChE1 is now resistant to 5 x 10(-4) M propoxur. The possibility that AChE1 and AChE2 are products of tissue-specific posttranslational modifications of a single gene is discussed, but we suggest, based on recent results obtained at the molecular level in mosquitoes, that they are encoded by two different genes.