Binding of low density and very low density lipoproteins to liver plasma membranes of copper-deficient rats

The binding of rat LDL and rabbit β-VLDL to liver plasma membranes of copper-deficient rats was examined. Characterization experiments demonstrated binding of both lipoprotein fractions to be relatively insensitive to treatment with pronase, EDTA, excess CaCl₂, or heparin. Competitive displacement experiments demonstrated that the binding reaction is not dependent on specific apolipoprotein ligands and imply a nonspecific binding site. These results indicate binding independent of the LDL or chylomicron remnant receptor. Copper deficiency had no effect on the total binding of either LDL or β-VLDL over a wide range of label concentration. The data indicate that hepatic membranes from copper-deficient rats do not exhibit altered binding capacity for LDL or β-VLDL and provide evidence that an impairment in receptor-mediated binding of lipoproteins does not contribute to the hypercholesterolemia observed in copper-deficient rats.