Figure 7.

SR-BI-mediated cholesterol efflux is impaired with aspartic acid mutations at L427, F430, Y431, and L434. COS-7 cells expressing empty vector, WT-SR-BI, or aspartic acid mutants were pre-labeled with [³H]-cholesterol and incubated with HDL (50 μg/ml) for 4 h at 37 °C. Scintillation counts for the media and cellular lipids were used to calculate percent efflux (media counts/[cellular + media] counts x 100%). Percent efflux values were normalized to average WT-SR-BI values (WT-SR-BI = 100%). Data represent the mean ± SD for three to four independent transfections (n = 4), each performed in quadruplicate. As determined by one-way ANOVA with Dunnett’s multiple comparisons tests, ∗∗∗p < 0.001 versus WT-SR-BI. HDL, high-density lipoprotein; SR-BI, scavenger receptor class B type I; WT, wildtype.