Figure 5.

How ezrin cleavage initiates actin polymerisation. In (a), the position of the membrane in relation to the plasma membrane is stable and is also shown in Figure 2. In (b), the ezrin linkage is broken by the action of activated µ-calpain, which results in (c) the establishment of the Brownian ratchet and the growth of actin polymers ‘pushing out’ the plasma membrane. In (d), the actin polymer is sufficiently long enough for branch points to be added actin polymerisation continues to push out the plasma membrane. The arrows at the side of a, b, c and d show the distance from the plasma membrane to the cortical actin network increasing.