Apolipoprotein E-mediated binding of hypertriglyceridemic very low density lipoproteins to isolated low density lipoprotein receptors detected by ligand blotting.
HTG-VLDL1, like LDL, bind with high affinity to electrophoretically transferred, isolated LDL receptors partially purified from bovine adrenal glands. Ligand blotting techniques show that binding is calcium dependent; little or no binding of LDL or HTG-VLDL1 is observed in the presence of 10 mM EDTA. HTG-VLDL1 does not bind in the presence of 7 mM suramin, an inhibitor of LDL binding to the LDL receptor. Pretreatment of LDL with either thrombin or trypsin does not affect apoB-mediated LDL binding to the LDL receptor. ApoE-mediated binding of HTG-VLDL1 to the blotted LDL receptor is abolished or greatly decreased by thrombin treatment of HTG-VLDL1; trypsin treatment of HTG-VLDL1 abolishes binding. Reincorporation of apoE into trypsinized HTG-VLDL1 restores binding. These studies demonstrate unequivocally that HTG-VLDL1 bind to the LDL receptor, that the binding of HTG-VLDL1 to the isolated LDL receptor is mediated through the thrombin-accessible apoE, and that HTG-VLDL1 which bind via potentially dissociable apoE rather than non-transferable apoB can be used for ligand blotting.
D000818:Animals; D001055:Apolipoproteins B / Q000502:physiology; D001057:Apolipoproteins E / Q000502:physiology*; D002417:Cattle; D004492:Edetic Acid / Q000494:pharmacology; D006801:Humans; D006951:Hyperlipoproteinemias / Q000378:metabolism*; D066298:In Vitro Techniques; D008024:Ligands; D008077:Lipoproteins, LDL / Q000378:metabolism; D008079:Lipoproteins, VLDL / Q000378:metabolism*; D011973:Receptors, LDL / Q000378:metabolism*; D013917:Thrombin / Q000494:pharmacology; D014357:Trypsin / Q000494:pharmacology
D001055:Apolipoproteins B; D001057:Apolipoproteins E; D008024:Ligands; D008077:Lipoproteins, LDL; D008079:Lipoproteins, VLDL; D011973:Receptors, LDL; D004492:Edetic Acid; D014357:Trypsin; D013917:Thrombin