Department of Biology, Brandeis University, Waltham, MA 02454, USA.
Science. 2012 Jun 1;336(6085):1164-8. doi: 10.1126/science.1218062.
Interacting sets of actin assembly factors work together in cells, but the underlying mechanisms have remained obscure. We used triple-color single-molecule fluorescence microscopy to image the tumor suppressor adenomatous polyposis coli (APC) and the formin mDia1 during filament assembly. Complexes consisting of APC, mDia1, and actin monomers initiated actin filament formation, overcoming inhibition by capping protein and profilin. Upon filament polymerization, the complexes separated, with mDia1 moving processively on growing barbed ends while APC remained at the site of nucleation. Thus, the two assembly factors directly interact to initiate filament assembly and then separate but retain independent associations with either end of the growing filament.
细胞中相互作用的肌动蛋白组装因子共同发挥作用，但潜在机制仍不清楚。我们使用三色单分子荧光显微镜来研究肿瘤抑制因子腺瘤性结肠息肉病（APC）和formin mDia1 在细丝组装过程中的作用。由 APC、mDia1 和肌动蛋白单体组成的复合物启动肌动蛋白丝的形成，克服了加帽蛋白和 Profilin 的抑制作用。在细丝聚合后，复合物分离，mDia1 在生长的突刺末端上进行连续运动，而 APC 则留在成核部位。因此，这两个组装因子直接相互作用以启动细丝组装，然后分离，但与生长细丝的任一端保持独立的关联。
