FIGURE 1. ABCA1-mediated cholesterol efflux in the presence of WT apoA-I and apoA-I[E191A/H193A/K195A].

Cells labeled with 6 μCi/ml [³H]cholesterol for 24 h and treated with or without 0.3 mM cpt-cAMP for 24 h were incubated with 1 μM WT apoA-I and apoA-I[E191A/H193A/K195A] for 4 h at 37°C. Media and cells were collected separately and the radioactivity was measured as described in Experimental Procedures. The percent of [³H]cholesterol efflux represents the amount of the radioactivity released in the medium divided by the total radioactivity present in the culture medium and the cell lysate. The percent of the net cpt-cAMP-dependent [³H]cholesterol efflux was calculated as the difference in percent of cholesterol efflux between treated cells (total efflux) and untreated cells (cpt-cAMP independent efflux). Black and white bars show the percent of [³H]cholesterol efflux from cpt-cAMP treated and untreated cells, respectively. Shaded bars show the percent of the net cpt-cAMP-dependent [³H]cholesterol efflux. The numbers on top of the bars represent the cholesterol efflux relative to the WT control set to 100%. Values are the means ± S.D. from three independent experiments performed in duplicate.