Interaction of Fibrin with the Very Low-Density Lipoprotein (VLDL) Receptor: Further Characterization and Localization of the VLDL Receptor-Binding Site in Fibrin βN-Domains

Our recent study revealed that fibrin and the very low-density lipoprotein receptor (VLDLR) interact with each other through a pair of fibrin βN-domains and CR domains of the receptor and this interaction promotes transendothelial migration of leukocytes and thereby inflammation. The major objectives of this study were to further clarify the molecular mechanism of fibrin–VLDLR interaction and to identify amino acid residues in the βN-domains involved in this interaction. Our binding experiments with the (β15–66)2 fragment, which corresponds to a pair of fibrin βN-domains, and the VLDLR(1–8) fragment, consisting of eight CR domains of VLDLR, revealed that interaction between them strongly depends on ionic strength and chemical modification of all Lys or Arg residues in (β15–66)2 results in abrogation of this interaction. To identify which of these residues are involved in the interaction, we mutated all Lys or Arg residues in each of the three positively charged Lys/Arg clusters of the (β15–66)2 fragment, ...