Inhibitory effect of RAP on the interaction of the (β15-66)2 fragment with the VLDLR detected by SPR. (A) RAP (50nM; solid line), 500nM (β15-66)2 (dotted line), or their mixture [50nM RAP + 500nM (β15-66)2] (broken line), were added to immobilized VLDLR and their association/dissociation was monitored in real time. (B) The same mixture of RAP and (β15-66)2 was added after the addition of 50nM RAP (solid line) or 500nM (β15-66)2, (broken line); arrows indicate injection of the mixture. The curves are representative of 2 independent experiments.