Figure 4.
ApoB secretion is reduced in vitro by transport-defective LDLR mutants. (A) Intracellular (open bars) and secreted (filled bars) apoB100 levels from Ldlr−/− hepatocytes that were transfected with plasmid DNAs encoding various LDLR mutants and β-gal control. (B) Intracellular and secreted apoB48 levels from the same samples shown in A. Values are mean ± SE (n = 6), are expressed as relative counts, and are corrected for milligrams of protein, as well as mean albumin levels in each sample. Samples indicated with an * differ significantly from secreted apoB in cells expressing β-gal (P ≤ 0.01, Student's t test). There was no significant difference in secreted apoB between cells expressing β-gal and those expressing the nonbinding form of LDLRKDEL (P ≥ 0.64, Student's t test).