Fig. 6.

Release of I¹²⁵-LDL as a function of time. Twelve mutant and WT receptors were immobilized and prebound with I¹²⁵-LDL using the solid phase binding assay. To take into account that mutants might bind I¹²⁵-LDL differently or display varying amounts of nonspecific release, the acid-specific portion of ligand release was calculated, i.e., specific release is (% release at pH 5) – (% release at pH 8). Ligand release was measured after 2.5, 5, 10, and 20 min at 4°C using release buffers at pH 5 or pH 8 (see Materials and Methods). Release by each mutant and WT was assayed in triplicate for each pH, and error bars show the SE of the mean.