Diagram describing yeast polarisome model.

<p>(<b>A</b>) Input driven recruitment of cytoplasmic Bni1 by membrane bound active Cdc42 (Cdc42a). (<b>B</b>) Bni1 on the membranes nucleates and polymerizes actin cables. (<b>C</b>) Actin cables direct transport of Spa2 from the cytoplasm to the membrane. (<b>D</b>) Spa2 provides positive feedback as it recruits cytoplasmic Bni1 to the membrane and inhibits actin depolymerization.