Calcium-dependent membrane binding of the rabbit reticulocyte lipoxygenase in vitro. The purified rabbit 15-LOX (30 nanokatals/mL) was incubated for 5 minutes with erythrocyte ghosts (2 mg/mL) and SMP (1 mg/mL) in the presence (0.5 mmol/L) and absence of calcium chloride. Sample work-up, electrophoresis, and immunoblotting are described in Materials and Methods. (A) Supernatant in the presence of calcium, (B) membrane pellet in the presence of calcium, (C) supernatant in the absence of calcium, (D) membrane pellet in the absence of calcium.