Kordeli E, Cartaud J, Nghiêm H O, Changeux J P
Biol Cell. 1987;59(1):61-8. doi: 10.1111/j.1768-322x.1987.tb00516.x.
The subcellular distribution of soluble and filamentous forms of actin in Torpedo marmorata electrocyte was investigated by cytochemical methods. Under conditions of adequate fixation of the electric tissue, two different monoclonal anti-actin antibodies revealed, in situ, actin only in the cytoplasm, never in association with the innervated and non-innervated membranes. On the other hand, a fluorescent derivative of phalloidin labeled the polymerized F-form of actin at the level of the non-innervated membrane and of the nerve terminals. However, after homogenization of the tissue, innervated membrane fragments, which still comprised cytoskeletal filaments, were systematically labeled on their cytoplasmic face. In these membrane fragments, cytoplasmic actin was never observed on the cytoskeleton. These results point to a redistribution of actin during tissue fractionation. The secondary binding of actin to the cytoplasmic surface of the postsynaptic membrane is consistent with its known in vitro interaction with the membrane-bound, 43 kd (v1) protein. Thus, at variance with the 43 kd protein, actin is not a prominent component of the mature Torpedo postsynaptic domain, and its suggested contribution to the stabilization of the AchR in the postsynaptic membrane should be reconsidered.
利用细胞化学方法研究了电鳐（Torpedo marmorata）电细胞中肌动蛋白的可溶性和丝状形式的亚细胞分布。在电组织充分固定的条件下，两种不同的抗肌动蛋白单克隆抗体在原位仅在细胞质中检测到肌动蛋白，从未在受神经支配和未受神经支配的膜上检测到。另一方面，鬼笔环肽的荧光衍生物在未受神经支配的膜和神经末梢水平标记了聚合的F-肌动蛋白形式。然而，在组织匀浆后，仍然包含细胞骨架细丝的受神经支配的膜碎片在其细胞质面上被系统地标记。在这些膜碎片中，从未在细胞骨架上观察到细胞质肌动蛋白。这些结果表明在组织分级分离过程中肌动蛋白发生了重新分布。肌动蛋白与突触后膜细胞质表面的二次结合与其在体外与膜结合的43kd（v1）蛋白的相互作用一致。因此，与43kd蛋白不同，肌动蛋白不是成熟电鳐突触后结构域的主要成分，其对突触后膜中乙酰胆碱受体稳定作用的建议应重新考虑。
