在长蛸视神经节中[3H]-乙酰胆碱和125I-α-银环蛇毒素的结合位点。

Binding sites for [3H]-acetylcholine and 125I-alpha-bungarotoxin in the optic ganglion of Loligo pealii.

Chen S J, Spathis R, Schmidt J

Department of Biochemistry, State University, Stony Brook, NY 11794.

Comp Biochem Physiol C Comp Pharmacol Toxicol. 1988;90(2):317-23. doi: 10.1016/0742-8413(88)90005-9.

Abstract

In the optic ganglion of Loligo pealii, binding sites for [3H]-acetylcholine (KD: 5.2 x 10(-7) M; Bmax: 1.7 x 10(-11) mol/g tissue) and 125I-alpha-bungarotoxin (KD: 3.3 x 10(-9) M; Bmax: 9.7 x 10(-11) mol/g tissue) were observed. 2. Both sites are blocked by nicotinic compounds, but differ significantly in their affinity for individual ligands, with the acetylcholine site preferentially binding agonists, and the toxin site, antagonists. 3. The acetylcholine site is substantially more thermolabile than the toxin site. 4. A partial separation of the two binding activities is accomplished by sucrose density centrifugation. 5. These observations and a comparison with other tissues (Torpedo californica electroplaque; chick optic lobe; rat brain) suggest the presence, in the squid, of more than one kind of neuronal nicotinic receptor.

摘要

在枪乌贼的视神经节中，观察到了[3H]-乙酰胆碱的结合位点（解离常数KD：5.2×10⁻⁷ M；最大结合量Bmax：1.7×10⁻¹¹ mol/g组织）和¹²⁵I-α-银环蛇毒素的结合位点（KD：3.3×10⁻⁹ M；Bmax：9.7×10⁻¹¹ mol/g组织）。2. 这两个位点均被烟碱类化合物阻断，但它们对单个配体的亲和力有显著差异，乙酰胆碱位点优先结合激动剂，而毒素位点优先结合拮抗剂。3. 乙酰胆碱位点比毒素位点对热更不稳定。4. 通过蔗糖密度离心可实现两种结合活性的部分分离。5. 这些观察结果以及与其他组织（加州电鳐的电板；鸡视叶；大鼠脑）的比较表明，在鱿鱼中存在不止一种神经元烟碱受体。