研究成果概要：A cell moves by repeating expansion of the front andcontraction of the rear. This cell movement requires proper int...A cell moves by repeating expansion of the front andcontraction of the rear. This cell movement requires proper intracellularlocalizations of actin binding proteins (ABPs), particularly segregation ofmyosin II and cofilin. The segregation mechanism remains unclear, but we havebeen studying possible involvement of the autonomy of the actin/ABP system. Myosinand cofilin form segregated patches along individual actin filaments, due tomutually exclusive/cooperative actin binding of the ABPs (Ngo et al., 2016),but each patch is too small to explain the cells-sized segregation of the two proteinsin vivo. Here, we showed that the ABPs formed cell-sized segregation on the actinnetwork whose density was high enough for each myosin filament to bind multipleactin filaments simultaneously. We also showed that the cell-sized segregationwas not formed when myosin and cofilin were added simultaneously, but it wasformed when myosin were added before cofilin. These results suggest that, in additionto the mutually exclusive/cooperative binding of the ABPs, the following two elementsof the self-regulatory mechanism of actin/ABP system are important for thesegregation. First, crosslinking of actin filaments by myosin filaments.Second, the physical condition that the filament-filament distance is smallerthan the size of a myosin filament, which makes the myosin crosslink effective.