Figure 4.

ATPase activity of zebrafish Abcb4 and Abcb5 is similar to that of human P-gp. (a) The vanadate-sensitive activity of zebrafish Abcb4, zebrafish Abcb5 and human P-gp was determined as outlined in Materials and Methods using membranes isolated from Dr Abcb4, Dr Abcb5 or MDR-19 cells, respectively. (b) Basal P-gp ATPase activity (DMSO) was compared to activity in the presence of 50 µM verapamil, or in the presence of 1 µM tariquidar. Graphs from (a) and (b) depict average values from three independent experiments (error bars ± SD).