Fig. 2.

Modeling notation and response of collective polarization to uniform and graded inputs. (A) Fat in cell i (f_i) binds to Ds in cell j (d_j) to form complexes U_ij. (B) Gray curve shows polarization (q/s) as a function of heterodimer levels in the absence of any graded input signals. Spontaneous polarization at critical heterodimer concentration in response to a uniform input, as described by Eq. 6, is shown. (C) Black curve shows polarization (q/s) as a function of heterodimer levels under graded expression. The polarization response to a gradient is level-dependent. Robust polarization enhancement occurs when Fat = Ds.