C-terminal lysine residues are important for PF4 inhibition of LDL degradation.

Degradation of ¹²⁵I-LDL (5 nM) in the absence (control) or presence of WT or mutant PF4 (10 μg/mL) by LDL-R–transfected CHO cells. Data are shown relative to control and are the mean ± SEM of 3 independent experiments, each performed in triplicate. QE2, K61, and K65 are mutant PF4 proteins described in the text.