Böhm K J, Vater W, Fenske H, Unger E
Biochim Biophys Acta. 1984 Jul 30;800(2):119-26. doi: 10.1016/0304-4165(84)90049-7.
In order to demonstrate the effect of microtubule-associated proteins on the protofilament number of microtubules, we used different systems of microtubule formation in vitro in which these proteins are either functionally eliminated (by DNA or glycerol) or absent (purified tubulin). The results obtained by electron microscopy of ultrathin-sectioned material indicate that under standard conditions in the presence of microtubule-associated proteins microtubules are formed consisting predominantly of 14 protofilaments. In cases of deficiency of microtubule-associated proteins, the mean value of the protofilament number is lower, and the protofilament number within the microtubule population varies remarkably. On the other hand, the action of microtubule-associated proteins is enhanced by histones resulting in increased protofilament numbers. A model is proposed illustrating that the quality and the quantity of microtubule-associated proteins bound to microtubules determine the curvature between the protofilaments and restrict the variety of their binding angles. In this way the microtubule-associated proteins may be regarded as an important factor in determining the structural fidelity of microtubules.
为了证明微管相关蛋白对微管原纤维数量的影响，我们在体外使用了不同的微管形成系统，在这些系统中，这些蛋白要么功能被消除（通过DNA或甘油），要么不存在（纯化的微管蛋白）。通过对超薄切片材料进行电子显微镜观察得到的结果表明，在标准条件下，存在微管相关蛋白时，形成的微管主要由14条原纤维组成。在微管相关蛋白缺乏的情况下，原纤维数量的平均值较低，并且微管群体中原纤维的数量变化显著。另一方面，组蛋白会增强微管相关蛋白的作用，导致原纤维数量增加。提出了一个模型，说明与微管结合的微管相关蛋白的质量和数量决定了原纤维之间的曲率，并限制了它们结合角度的多样性。通过这种方式，微管相关蛋白可被视为决定微管结构保真度的一个重要因素。
