Figure 4.

Thirteen amino acids from ECL1 and five residues from ECL4 of human P-gp are required for binding of UIC2 antibody to mouse P-gp. (A) Schematic of the mouse-ECL1&4-h18 chimera structure. The ECLs 1 and 4 are enlarged in the insets. Mouse-specific amino acids are in red and replaced human P-gp amino acids are shown in blue. (B) Representative histograms of antibody binding to the mouse-ECL 1&4-h18 chimera. Replacing thirteen residues in ECL1 and five amino acids in ECL4 of mouse P-gp completely recovered binding of the human P-gp-specific monoclonal UIC2 antibody as well as MRK-16 and 4E3.