Carbonetto S T, Fambrough D M, Muller K J
Proc Natl Acad Sci U S A. 1978 Feb;75(2):1016-20. doi: 10.1073/pnas.75.2.1016.
alpha-Bungarotoxin binds selectively to chick sympathetic neurons that are responsive iontophoretically applied acetylcholine. alpha-Bungarotoxin (125 nM) does not affect the response of cultured neurons to acetylcholine, nor does it affect a cholinergic synaptic potential recorded from sympathetic ganglia. d-Tubocurarine (100 muM) inhibits alpha-bungarotoxin binding and blocks acetylcholine receptor function in both preparations, but alpha-bungarotoxin does not protect acetylcholine receptors against d-tubocurarine blockade of acetylcholine responses. The receptor for alpha-bungarotoxin can be extracted from neuronal membranes with nonionic detergents and, when assayed by velocity sedimentation in sucrose gradients, sediments at a rate faster than that of skeletal muscle acetylcholine receptors. Treatment of alpha-bungarotoxin-receptor complexes with glutaraldehyde (0.1%, wt/vol) increases their stability from a half-time for dissociation of 3.5 hr to greater than 6 days at 23 degrees. This permits a quantitative assay of alpha-bungarotoxin-receptor complexes after relatively long periods of velocity sedimentation. It is concluded that alpha-bungarotoxin does not bind to the acetylcholine-binding site of neuronal acetylcholine receptors. These results compel a reevaluation of studies that assume that alpha-bungarotoxin is a specific ligand for neuronal acetylcholine receptors.
α-银环蛇毒素选择性地结合对离子电泳施加乙酰胆碱有反应的鸡交感神经元。α-银环蛇毒素（125 nM）不影响培养神经元对乙酰胆碱的反应，也不影响从交感神经节记录的胆碱能突触电位。d-筒箭毒碱（100 μM）在两种制剂中均抑制α-银环蛇毒素的结合并阻断乙酰胆碱受体功能，但α-银环蛇毒素不能保护乙酰胆碱受体免受d-筒箭毒碱对乙酰胆碱反应的阻断。α-银环蛇毒素的受体可用非离子去污剂从神经元膜中提取，当通过蔗糖梯度中的速度沉降进行分析时，其沉降速度比骨骼肌乙酰胆碱受体快。用戊二醛（0.1%，重量/体积）处理α-银环蛇毒素-受体复合物可将其稳定性从解离半衰期3.5小时提高到23℃下大于6天。这允许在相对较长时间的速度沉降后对α-银环蛇毒素-受体复合物进行定量分析。结论是α-银环蛇毒素不与神经元乙酰胆碱受体的乙酰胆碱结合位点结合。这些结果促使人们重新评估那些认为α-银环蛇毒素是神经元乙酰胆碱受体特异性配体的研究。
