Schematic of the kinetic model. Model species are denoted by Roman letters, and reactions are in italics. Initial conditions and rate constants are listed in Tables I and II, and differential equations are in Table S1. For PIP₂ and IP₃ binding to KCNQ and PH, the association reactions are referred to as forward reactions, and dissociation reactions are referred to as reverse reactions. KCNQ2/3 current depends on the square of PIP₂-bound KCNQ2/3 subunits (PIP₂_KCNQ2/3).