Inoue I, Pant H C, Tasaki I, Gainer H
J Gen Physiol. 1976 Oct;68(4):385-95. doi: 10.1085/jgp.68.4.385.
Proteins in the inner surface of the squid axon membrane were labeled by intracellular perfusion of [3H]N-ethylmaleimide (NEM), which forms covalent bonds with free sulfhydryl groups. The excitability of the axon was unaffected by the [3H]NEM perfusion. After washout of the unbound label, the perfusate was monitored for the release of labeled proteins. Labeled proteins were released from the inner membrane surface by potassium depolarization of the axon only in the presence of external calcium ions. Replacement of the fluoride ion in the perfusion medium by various anions also caused labeled protein release. The order of effectiveness was SCN- greater than Br- greater than Cl- greater than F-. The extent of labeled protein release by the various anions was correlated with their effects on axonal excitability. The significance of these results is discussed.
通过用[3H]N - 乙基马来酰亚胺（NEM）进行细胞内灌注，对鱿鱼轴突膜内表面的蛋白质进行标记，NEM会与游离巯基形成共价键。轴突的兴奋性不受[3H]NEM灌注的影响。在洗去未结合的标记物后，监测灌注液中标记蛋白质的释放情况。只有在存在外部钙离子的情况下，轴突的钾离子去极化才会导致标记蛋白质从内膜表面释放。用各种阴离子替代灌注介质中的氟离子也会导致标记蛋白质释放。其有效性顺序为：SCN-＞Br-＞Cl-＞F-。各种阴离子引起的标记蛋白质释放程度与它们对轴突兴奋性的影响相关。讨论了这些结果的意义。
