FIGURE 1.

Phases of actin and myosin II self-organization. In all figures, the actin concentration is 2.4 μM. The different types of assembly architecture are shown as a function of the ratio of myosin II minifilaments to actin filaments and the ATP-dependent activity of the motors (active sliding or passive crosslinking). When the motors are active, a state of dynamic disorder persists. When the ATP is diminished to a point where the activity of the motors is below a critical threshold, passive crosslinking dominates, triggering a spontaneous transition to different types of ordered actomyosin aggregates, as indicated. (Scale bar is 20 μm.)