Function of Myosin VI

肌动蛋白为基础的分子运动肌球蛋白VI在胞吞摄取途径中起作用，无论是在网格蛋白介导的摄取的早期阶段，还是在后期转运到/从早期核内体。本研究采用光漂白后荧光恢复法（FRAP）检测内吞过程中肌球蛋白VI的周转率。结果表明，肌凝蛋白VI在胞吞结构上动态翻转，其半衰期特征与肌凝蛋白VI在网格蛋白包覆结构上的大插入异构体和早期核内体上的无插入异构体相同。这个半衰期由肌凝蛋白VI结合伙伴Dab2共享，并且全长肌凝蛋白VI和货物结合尾部区域是相同的。人工二聚的肌凝蛋白VI在网格蛋白包被结构上的半衰期慢了四倍，这表明野生型肌凝蛋白VI不是稳定的二聚体，而是作为单体或单体/二聚体平衡。综上所述，这些FRAP结果提供了对肌球蛋白VI的基本周转动力学和单体/二聚体性质的见解。

The actin-based molecular motor myosin VI functions in the endocytic uptake pathway, both during the early stages of clathrin-mediated uptake and in later transport to/from early endosomes. This study uses fluorescence recovery after photobleaching (FRAP) to examine the turnover rate of myosin VI during endocytosis. The results demonstrate that myosin VI turns over dynamically on endocytic structures with a characteristic half life common to both the large insert isoform of myosin VI on clathrin-coated structures and the no insert isoform on early endosomes. This half life is shared by the myosin VI binding partner Dab2 and is identical for fulllength myosin VI and the cargo-binding tail region. The four fold slower half life of an artificially dimerized construct of myosin VI on clathrin-coated structures suggests that wildtype myosin VI does not function as a stable dimer, but either as a monomer or in a monomer/dimer equilibrium. Taken together, these FRAP results offer insight into both the basic turnover dynamics and the monomer/dimer nature of myosin VI.