Figure 2. Competitive binding analysis for PMP-OVA and PMP-SYK in displacement of PMP-BSA from M6P-IGF2R-FLAG constructs immobilized on M2-α-FLAG affinity resin.
Cell lysates, containing equimolar amounts of the indicated expressed soluble receptors A. were immunoprecipitated with M2 α-FLAG affinity resin and tested for direct binding to 125I-PMP-BSA, 125I-hGUS, or 125I-IGF-II B., or incubated with increasing concentrations of PMP-OVA C., or PMP-SYK D. to measure the ability of the PMP-ligands to displace the radiolabeled tracer, 125I-PMP-BSA (5 × 105 cpm). Data were analyzed as described in the legend to Figure 1. Data for M6P and G6P were analyzed in parallel as positive and negative controls, respectively. The curves for M6P for each expressed soluble receptor were measured and represented as a displacement curves for a single immunoprecipitated soluble receptor. G6P had no apparent displacement activity for any of the test ligands, and these curves have been omitted for clarity.