Shoeman R L, Traub P
Max-Planck-Institut für Zellbiologie, Ladenburg, Federal Republic of Germany.
Bioessays. 1993 Sep;15(9):605-11. doi: 10.1002/bies.950150906.
The assembly of intermediate filaments is a fundamental property of the central rod domain of the individual subunit proteins. This rod domain, with its high propensity for alpha-helix formation, is the common and identifying feature of this family of proteins. Assembly occurs in vitro in the absence of other proteins or exogenous sources of energy; in vivo, it appears as if other factors, as yet poorly understood, modulate the assembly of intermediate filaments. Parallel, in-register dimers form via coiled-coil interactions of the rod domain. Tetramers may form from staggered arrays of parallel or antiparallel arrangements of dimers. Higher-order polymerization, which occurs spontaneously if the ionic strength of a mixture of dimers and tetramers is raised, proceeds rapidly through poorly described intermediates to the final 10 nm filament. This process is dependent on and modulated by the non-alpha-helical end domains, as well as those amino acids present at the very beginning and end of the rod domain. The interactions governing tetramer formation are most probably the same ones that are responsible for the lateral and longitudinal associations within intermediate filaments.
中间丝的组装是单个亚基蛋白中央杆状结构域的基本特性。这个杆状结构域具有很高的形成α-螺旋的倾向，是这类蛋白质的共同识别特征。在没有其他蛋白质或外源能量来源的情况下，组装可在体外发生；在体内，似乎有其他尚未完全了解的因素调节中间丝的组装。平行、对齐的二聚体通过杆状结构域的卷曲螺旋相互作用形成。四聚体可能由二聚体的平行或反平行排列的交错阵列形成。如果提高二聚体和四聚体混合物的离子强度，高阶聚合会自发发生，通过描述不清的中间体迅速形成最终的10纳米细丝。这个过程取决于非α-螺旋末端结构域以及杆状结构域起始和末端的氨基酸，并受其调节。控制四聚体形成的相互作用很可能与中间丝内横向和纵向缔合的相互作用相同。
