... with tyrosines of the protein.However, analysis in single-point binding assays showedonly 50–60% of the cell-associated [125I]PCSK9 could beinhibited in the presence of a large excess of unlabeledPCSK9, ... toHepG2 cells. First, the number of LDLRs on HepG2cells increased following growth in the absence of lipo-proteins, and there was a corresponding increase in the binding of [125I]TC-PCSK9 and [125I]TC-PCSK9-D374Y. ... Second, the extent of specific binding of both[125I]TC-labeled ligands was a linear function of the cell density. Finally, the binding is specific, as the Table 2. Parameters obtained from kinetic...