PFIC II mutations exhibit heterogeneous effects on Bsep taurocholate transport activity. (a) Sf9 cell vesicles (100 μg) expressing Bsep or Bsep PFIC II mutant were analyzed by Western blotting as indicated. (b) ATP-dependent [³H]taurocholate transport was measured using membrane vesicles isolated from Sf9 cells expressing Bsep or PFIC II mutants. Vesicle uptake of [³H]taurocholate (2.5 μM) was determined in the presence and absence of ATP (5 mM). Data represent the mean ± SD of three determinations. The difference between taurocholate uptake measured in the presence and absence of ATP was defined as ATP-dependent taurocholate uptake.