Journal: The Journal of Biological Chemistry
Article Title: Factor VIII Interacts with the Endocytic Receptor Low-density Lipoprotein Receptor-related Protein 1 via an Extended Surface Comprising “Hot-Spot” Lysine Residues ♦
doi: 10.1074/jbc.M115.650911
Figure Lengend Snippet: Library of lysine to arginine replacements in the FVIII light chain identifies the contribution of multiple lysine residues in the interaction with LRP1 cluster II. Association and dissociation of LRP1 cluster II to FVIII light chain variants were assessed by SPR analysis employing a BIAcore 3000 biosensor (Biacore AB). The anti-C2 antibody CLB-EL14 IgG4 (26 fmol/mm−2) was immobilized onto a CM5 sensor chip using the amine coupling method according to the manufacturer's instructions. Subsequently, FVIII light chain variants were bound to the anti-C2 antibody at a density of 17 fmol/mm−2. LRP1 cluster II (0.2–200 nm) was passed over the FVIII light chain variants in a buffer containing 150 mm NaCl, 5 mm CaCl2, 0.005% (v/v) Tween 20, and 20 mm Hepes (pH 7.4) at 25 °C with a flow rate of 20 μl/min. The sensor chip surface was regenerated three times after each concentration of LRP1 cluster II using the same buffer containing 1 m NaCl. Binding to FVIII light chain variants was corrected for binding in the absence of FVIII. Binding data during the association phase were fitted in a one-phase exponential association model. A, representative experiment for the interaction between LRP1 cluster II and wild type FVIII light chain. B, on each SPR sensor chip, we included a control channel (only CLB-EL14 IgG4), wild type FVIII light chain, and two FVIII light chain variants. Therefore, wild type FVIII light chain was analyzed multiple times (n = 14) C and D, representative experiments for variants. E, the KD for LRP1 cluster II for the FVIII light chain variants was compared with the KD of wild type FVIII light chain (n = 14, degrees of freedom = 13, *, p < 0.10, t value = 2.16, ***, p <0.001, t value = 4.22) using a two-tailed Student's t test. Error bars indicate ± S.D.
Article Snippet: Surface Plasmon Resonance Analysis Association and dissociation of LRP1 cluster II to FVIII light chain and FVIIIdB variants were assessed by SPR analysis employing a BIAcore 3000 biosensor (Biacore AB, Uppsala, Sweden).
Techniques: Concentration Assay, Binding Assay, Control, Two Tailed Test