Figure 1.

Characteristics of bradykinin binding to OppA. (A) Time-dependent binding of bradykinin to proteoliposomes containing OppA (●) and liposomes without OppA (■). The final OppA concentration was 20 μg/ml, which corresponds to a lipid concentration of the liposomes of 4 mg/ml; the [³H]bradykinin concentration was 0.1 μM. (B) Bradykinin binding as a function of the OppA concentration. (C) Determination of the dissociation constant (K_d) for bradykinin binding to OppA. The experimental data were fitted to a hyperbole from which the K_d (0.09 ± 0.01 μM) and the B_max (14.6 ± 0.3 nmol/mg protein) were estimated.