The functional significance of microtubule quaternary structure

微管（MT）是α-β微管蛋白二聚体的细长聚合物，其形成有丝分裂纺锤体、轴丝和细胞骨架。微管蛋白亚基首尾相连形成原丝（pfs），通常13个pfs横向相连形成MT。MT是“可塑性”聚合物，也就是说微管蛋白可以形成横向和纵向曲率不同的结构。这种可塑性是由微管蛋白二聚体之间的连接的灵活性，并可能给予微管其独特的机械性能。然而，在控制微管晶格的四级结构方面，结构可塑性给细胞带来了挑战。

Microtubules (MTs) are long, slender polymers of α-β tubulin dimers that form the mitotic spindle, axonemes, and the cytoskeleton. Tubulin subunits associate head-to-tail to form protofilaments (pfs), and typically 13 pfs are associated laterally to form the MT. MTs are "plastic" polymers, which is to say that tubulin can form structures that differ in their lateral and longitudinal curvature. This plasticity is made possible by flexibility in the links between tubulin dimers and may give microtubules their unique mechanical properties. Structural plasticity creates a challenge for cells, however, in terms of controlling the quaternary structure of the microtubule lattice.