Fig. 2

Increasing intracellular sterol release rates decrease the attainable sterol asymmetry in the PM. Steady state transbilayer sterol distribution (a ratio Q, Eq. 11) and percent sterol in the inner leaflet (b) as function of the passive sterol distribution between both PM leaflets (q₂) for the indicated rate constants of intracellular sterol release (k₃) for the irreversible sterol import model. A ratio Q = 1 corresponds to a symmetric sterol distribution between both leaflets, while Q > 1; Q < 1 means sterol enrichment in the inner and outer leaflet, respectively. Other parameters were v₁ = 1 mol/s and k_− 2 = 1 s^− 1, respectively