Figure 4.

RA binds to the M6P/IGF-II receptor with high affinity. Partially purified M6P/IGF-II receptor from neonatal rat serum was incubated with increasing concentrations of [³H]RA in the absence (total binding) or presence (nonspecific binding) of 200-fold excess unlabeled RA. Nonspecific binding was subtracted from total binding and plotted as specific binding. (Inset) Specific RA binding to M6P/IGF-II receptor was transformed by Scatchard analysis and plotted. Linear regression yielded a K_D of 2.4 nM (r = 0.97).