FIGURE 2.
Anterograde transport from the ER is required for LDLR-dependent degradation of apoB. Ldlr-/- primary hepatocytes were infected with Ad-β-Gal (β-Gal) or Ad-LDLR-WT (WT) at a titer of 0.8 × 108 pfu/dish. In A, cells were radiolabeled with [35S]Met/Cys for 1 h and chased in cold media for 2 h. AU, arbitrary units. In B, cells were chased in cold medium with 10 μg/ml BFA for 2 h and then further chased in the absence of BFA for 3 h. In both A and B, total levels of apoB-100, apoB-48, and albumin were calculated as the sum of protein-normalized cellular and secreted levels. The data are expressed as the mean fractional decrease in LDLR-expressing cells relative to β-Gal-expressing cells (n = 5). Black bars indicate total protein levels; white bars indicate cellular protein levels. Similar results were obtained in three independent experiments. *, p < 0.05, **, p < 0.01, Student's t test.