Lee T, Langford K J, Askham J M, Brüning-Richardson A, Morrison E E
CRUK Clinical Centre at Leeds, Division of Cancer Medicine Research, St James's University Hospital, Leeds, UK.
Oncogene. 2008 Apr 10;27(17):2494-500. doi: 10.1038/sj.onc.1210867. Epub 2007 Oct 29.
The microtubule (MT)-associated protein EB1 localizes to and promotes growth at MT plus ends. The MT depolymerizing kinesin MCAK has also been reported to track growing MT plus ends. Here, we confirm that human MCAK colocalizes with EB1 at growing MT ends when expressed as a GFP fusion protein in transfected cells. We show that MCAK associates with the C-terminus of EB1 and EB3 but much less efficiently with RP1. EB1 associates with the N-terminal localization and regulatory domain in MCAK but not with the motor domain of the protein. The interaction is competitive with the binding of other EB1 ligands and does not require MTs. Knockdown of EB1 expression using siRNA impaired the ability of GFP-MCAK to localize to MT tips in transfected cells. We propose that MCAK is targeted to growing MT ends by EB1, that MCAK is held in an inactive conformation when associated with EB1 and that this could provide the basis for a mechanism that facilitates rapid switching between phases of MT growth and depolymerization.
微管（MT）相关蛋白EB1定位于MT正端并促进其生长。据报道，MT解聚驱动蛋白MCAK也追踪生长中的MT正端。在这里，我们证实，当在转染细胞中作为GFP融合蛋白表达时，人MCAK与EB1在生长中的MT末端共定位。我们表明，MCAK与EB1和EB3的C末端相关，但与RP1的结合效率低得多。EB1与MCAK的N末端定位和调节域相关，但与该蛋白的运动域无关。这种相互作用与其他EB1配体的结合具有竞争性，并且不需要MT。使用siRNA敲低EB1表达会损害GFP-MCAK在转染细胞中定位于MT末端的能力。我们提出，MCAK通过EB1靶向生长中的MT末端，MCAK与EB1结合时处于无活性构象，这可能为促进MT生长和解聚阶段之间快速转换的机制提供基础。
