Alonso Maria C, Drummond Douglas R, Kain Susan, Hoeng Julia, Amos Linda, Cross Robert A
Molecular Motors Group, Marie Curie Research Institute, The Chart, Oxted, Surrey RH8 0TL, UK.
Science. 2007 Apr 6;316(5821):120-3. doi: 10.1126/science.1136985.
Kinesin-1 is a two-headed molecular motor that walks along microtubules, with each step gated by adenosine triphosphate (ATP) binding. Existing models for the gating mechanism propose a role for the microtubule lattice. We show that unpolymerized tubulin binds to kinesin-1, causing tubulin-activated release of adenosine diphosphate (ADP). With no added nucleotide, each kinesin-1 dimer binds one tubulin heterodimer. In adenylyl-imidodiphosphate (AMP-PNP), a nonhydrolyzable ATP analog, each kinesin-1 dimer binds two tubulin heterodimers. The data reveal an ATP gate that operates independently of the microtubule lattice, by ATP-dependent release of a steric or allosteric block on the tubulin binding site of the tethered kinesin-ADP head.
驱动蛋白-1是一种双头分子马达，它沿着微管移动，每一步都由三磷酸腺苷（ATP）结合控制。现有的门控机制模型认为微管晶格起作用。我们发现未聚合的微管蛋白与驱动蛋白-1结合，导致微管蛋白激活二磷酸腺苷（ADP）的释放。在不添加核苷酸的情况下，每个驱动蛋白-1二聚体结合一个微管蛋白异二聚体。在腺苷酰亚胺二磷酸（AMP-PNP）（一种不可水解的ATP类似物）中，每个驱动蛋白-1二聚体结合两个微管蛋白异二聚体。这些数据揭示了一个独立于微管晶格运作的ATP门控，其通过ATP依赖的方式释放束缚在驱动蛋白-ADP头部微管蛋白结合位点上的空间位阻或变构阻滞。
