Fig. 7
Low sterol influx exerts control over sterol distribution between membrane pools for bi-molecular complex formation. Accounting explicitly for sterol complex formation with a limited number of phospholipids in the outer PM leaflet (PT1 = 300 nM), the inner PM leaflet (PT2 = 1000 nM) or the ER (PT1 = 600 nM) results in highly non-linear dependence of sterol distribution between the two PM leaflets (a) and between PM and ER (b) on sterol influx, particularly for low influx values. Here, the equilibrium constant for sterol complexation in the outer PM leaflet, q4, was varied as indicated in panel (a). All other parameters were set as described in legend to Fig. 6, above