FIG 4.

Effect of membrane-bound cholesterol on MA binding to stBLMs containing DOPC, DOPS and PI(4,5)P₂. The buffer consisted of 10 mM Na₂PO₄ and 50 mM NaCl (pH 7.4). (A and B) –myrMA adsorption isotherms (A) and +myrMA adsorption isotherms (B) at 15 mol% DOPS and 5 mol% PI(4,5)P₂ in the absence or presence of cholesterol. To visualize the effect of PI(4,5)P₂ specificity in binding DOPC/DOPS (80:20; same data as in Fig. 2A and B) is shown for a reference. Because the PI(4,5)P₂ headgroup has ∼4 anionic charges at neutral pH (45), the charge density of the DOPC/DOPS and DOPC/PI(4,5)P₂ stBLMs is comparable.