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. Author manuscript; available in PMC: 2015 Oct 1.
Published in final edited form as: Curr Opin Cell Biol. 2014 Jul 5;0:60–67. doi: 10.1016/j.ceb.2014.06.007

Figure 1. Actin polymerization as an excitable system.

Figure 1

A) Actin polymerization is organized as multiple wavelike (top) and oscillatory nucleation events (bottom, single oscillator denoted by circle) in motile cells, as visualized by the dynamics of the Wave Regulatory Complex (WRC) [9–11]. Waves that reach the cell boundary organize cellular protrusion. B) The behavior of these waves and oscillations are consistent with an excitable system, which typically has the topology of rapid positive feedback and delayed inhibition (components bound by black dotted line). Key components of the chemotactic signaling network and the flow of information to factors specifying actin assembly are depicted in gray. Candidates for the molecular basis of the positive and negative feedback loops (green and red arrows, respectively) are briefly summarized.