Moore R C, Durso N A, Cyr R J
Department of Biology, Penn State University, University Park 16802, USA.
Cell Motil Cytoskeleton. 1998;41(2):168-80. doi: 10.1002/(SICI)1097-0169(1998)41:2<168::AID-CM7>3.0.CO;2-A.
Elongation factor-1alpha (EF-1alpha), a highly conserved protein named for its role in protein translation, is also a microtubule-associated protein (MAP). We used high-resolution differential interference contrast microscopy to quantify the effect of substoichiometric amounts of EF-1alpha (isolated from Daucus carota) on the dynamic instability of microtubules assembled in vitro from either animal or plant tubulin. EF-1alpha modulates the dynamic behavior of microtubules assembled from either tubulin source, resulting in longer and more persistent microtubules. EF-1alpha, at a 1:20 molar ratio to tubulin, significantly (P < 0.05) reduces the frequency of catastrophe threefold and decreases shortening velocities almost twofold for microtubules assembled from animal tubulin. For microtubules assembled from plant tubulin, substoichiometric amounts of EF-1alpha significantly (P < 0.05) suppress the frequency of catastrophe greater than twofold and causes an almost threefold reduction in shortening velocities. Elongation velocities increase almost twofold and rescues, which are not observed in the absence of EF-1alpha, occur. In addition, calcium/calmodulin (Ca2+/CaM), which regulates the ability of EF-1alpha to bundle taxol-stabilized microtubules in vitro, also modulates the effect of EF-1alpha on the dynamic behavior of microtubules assembled in vitro from animal tubulin. Microtubule severing in the presence of EF-1alpha was never observed. These data support the hypothesis that EF-1alpha modulates the dynamic behavior of microtubules assembled in vitro in a Ca2+/CaM-dependent manner.
延伸因子-1α（EF-1α）是一种因在蛋白质翻译中发挥作用而得名的高度保守的蛋白质，它也是一种微管相关蛋白（MAP）。我们使用高分辨率微分干涉相差显微镜来量化亚化学计量的EF-1α（从胡萝卜中分离）对由动物或植物微管蛋白体外组装的微管动态不稳定性的影响。EF-1α调节从任何一种微管蛋白来源组装的微管的动态行为，导致微管更长且更持久。与微管蛋白的摩尔比为1:20时，EF-1α能显著（P < 0.05）将动物微管蛋白组装的微管的灾难频率降低三倍，并使缩短速度降低近两倍。对于植物微管蛋白组装的微管，亚化学计量的EF-1α能显著（P < 0.05）将灾难频率抑制两倍以上，并使缩短速度降低近三倍。伸长速度增加近两倍，并且出现了在没有EF-1α时未观察到的挽救现象。此外，钙/钙调蛋白（Ca2+/CaM）在体外调节EF-1α捆绑紫杉醇稳定微管的能力，它也调节EF-1α对动物微管蛋白体外组装的微管动态行为的影响。在EF-1α存在的情况下从未观察到微管切断现象。这些数据支持了EF-1α以Ca2+/CaM依赖的方式调节体外组装的微管动态行为这一假说。
