Lipoprotein binding to canine hepatic membranes. Metabolically distinct apo-E and apo-B,E receptors.

Hepatic membranes from adult dog livers have receptors which bind to lipoproteins containing the E apoprotein (the apo-E HDL,) but lack specific receptors for the apo-B-containing low density lipoproteins (LDL).Scatchard analysis of direct binding data for '251-apo-E HDL, revealed nonlinearity of the binding which could be resolved into two components, suggesting the presence of two separate binding sites.The binding site for apo-E HDL, that possessed the highest affinity ( K d = ' The abbreviations used are: apo, apoprotein; LDL, low density lipoproteins; HDL, high density lipoproteins ( d = 1.125-1.21);apo-E HDL,, cholesterol-induced plasma lipoproteins that contain the E apoprotein as the only protein constituent, are cholesteryl ester rich, and float at a lower density ( d = 1.006-1.02);K,,, equilibrium dissociation constant.