Edidin M, Fambrough D
J Cell Biol. 1973 Apr;57(1):27-37. doi: 10.1083/jcb.57.1.27.
Fluorescent antibody fragments of anti-muscle plasma membrane antibody bound as small fluorescent spots when applied by micropipetting to cultured myotubes. The spots were observed to enlarge with time. The rate of enlargement of fluorescent spots was greater when fragments were applied than when divalent antibody was used. It was also greater at 23 degrees -25 degrees C than at 0 degrees -4 degrees C. With glutaraldehyde-fixed cells no increase in the size of the spots was seen. The observations are consistent with the spread of fluorescent spots due to diffusion of surface protein antigens within the plane of a fluid membrane. From measurements of spot size against time, a diffusion constant of 1-3 x 10(-9) cm(2) s(-1) can be calculated for muscle plasma membrane proteins of mol wt approximately 200,000. This value is consistent with other observations on the diffusion of surface antigens and of labeled lipid molecules in synthetic and natural membranes.
当通过微量移液器将抗肌细胞膜抗体的荧光抗体片段施加到培养的肌管上时，它们会结合成小的荧光斑点。观察到这些斑点会随着时间的推移而扩大。与使用二价抗体时相比，施加抗体片段时荧光斑点的扩大速率更高。在23摄氏度至25摄氏度时的扩大速率也比在0摄氏度至4摄氏度时更高。对于用戊二醛固定的细胞，未观察到斑点大小增加。这些观察结果与由于表面蛋白抗原在流体膜平面内扩散而导致的荧光斑点扩散一致。根据斑点大小随时间的测量结果，可以计算出分子量约为200,000的肌细胞膜蛋白的扩散常数为1 - 3×10⁻⁹ cm² s⁻¹。该值与关于合成膜和天然膜中表面抗原及标记脂质分子扩散的其他观察结果一致。
