Figure 5. Cholesterol esterification in cells expressing ORP2.

(A) Effect of ORP2 overexpression on cholesterol esterification. The three inducible HeLa cell lines were labelled with [¹⁴C]cholesterol for 42 h in the absence (white bars) or presence (black bars) of 1 μg/ml doxycycline. Labelled FC and CEs were separated from cell extracts using HPTLC and quantified by liquid-scintillation counting. The results are shown as a percentage of ¹⁴C-labelled CEs of total labelled cholesterol (mean±S.E.M.; n=9, ***P<0.001, *P<0.05, t test). (B) Effect of ACAT inhibition on the efflux of [¹⁴C]cholesterol from control CHO or ORP2/CHO cells. Control (white bars) and ORP2/CHO A5a9 cells (black bars) were labelled with [¹⁴C]cholesterol for 42 h in the absence (no PKF) or presence (PKF) of an ACAT inhibitor (PKF 058-035). Cells were then incubated for 2 h in a medium containing 20% human serum. The radioactivity of the cells and the media was determined by liquid-scintillation counting. The results are shown as the percentage of radioactivity found in the medium (mean±S.E.M.; n=6, ***P<0.001, t test).