Chylomicron remnant and asialoglycoprotein metabolism are independent

Abstract

Because of the considerable similarities between the hepatic metabolism of chylomicron remnants and asialoglycoproteins, the hypothesis that they might share a cell surface receptor or a common step in internalization was tested. Unlabeled chylomicron remnants did not reduce the binding of 125I-asia-glycoprotein to plasma membranes, but did compete for 125I-chylomicron remnant binding. The converse also was true. This suggested the receptors were distinct. The two substances did not compete with each other for removal by the isolated perfused rat liver. This suggests that no potentially common post binding events can become rate limiting. In conclusion, despite similarities in their removal and metabolism, chylomicron remnants and asialoglycoproteins are metabolized independently.