Axelrod D, Ravdin P, Koppel D E, Schlessinger J, Webb W W, Elson E L, Podleski T R
Proc Natl Acad Sci U S A. 1976 Dec;73(12):4594-8. doi: 10.1073/pnas.73.12.4594.
We have made direct, quantitative measurements of the lateral motion and age-dependent distribution of acetylcholine receptors (AChR) on the surface of rat myotubes in primary culture. AChR were fluorescently marked with tetramethylrhodamine-labeled alpha-bungarotoxin and AChR lateral motion was measured by the fluoresence photobleaching recovery technique. We found two coexisting distinct classes of AChR: (i) mobile, uniformly distributed AChR that appear on all myotubes shortly after fusion from myoblasts; and (ii) immobile, dense, highly granular AChR in patches of 10-60 mum size that appear shortly after fusion and disappear after myotubes have become extensively interconnected. In addition, evidence of turnover of AChR labeled with tetramethylrhodamine-alpha-bungarotoxin is seen in the gradual internalization of surface fluorescence within 36 hr after labeling. The relevance of these results to an understanding of the membrane dynamics and localization of muscle AChR is discussed.
我们对原代培养的大鼠肌管表面乙酰胆碱受体（AChR）的横向运动及年龄依赖性分布进行了直接的定量测量。用四甲基罗丹明标记的α-银环蛇毒素对AChR进行荧光标记，并通过荧光光漂白恢复技术测量AChR的横向运动。我们发现了两类共存的不同AChR：（i）可移动的、均匀分布的AChR，它们在成肌细胞融合后不久出现在所有肌管上；（ii）不可移动的、密集的、高度颗粒状的AChR，呈10 - 60微米大小的斑块状，在融合后不久出现，在肌管广泛相互连接后消失。此外，在标记后36小时内表面荧光逐渐内化，可见到用四甲基罗丹明-α-银环蛇毒素标记的AChR有周转的证据。讨论了这些结果与理解肌肉AChR的膜动力学和定位的相关性。
