Rapid hepatic clearance of the canine lipoproteins containing only the E apoprotein by a high affinity receptor. Identity with the chylomicron remnant transport process

J Biol Chem. 1980 Mar 10;255(5):1804-7.

Abstract

The canine lipoproteins containing only the E apoprotein (apo-E HDLc), when perfused through a rat liver, display high affinity, receptor-mediated uptake, and saturation kinetics. These data indicate that the hepatic uptake of apo-E HDLc proceeds via a finite number of binding sites. The kinetic values determined for apo-E HDLc binding and uptake during a single-pass perfusion through a rate liver are: Km = 4.99 micrograms of protein . ml-1 and Vmax = 6.42 microgram of protein . g-1 . min-1. On a molar basis, the hepatic extraction of apo-E HDLc is almost equivalent to the high hepatic extraction of a class of lipoproteins that is most avidly removed from systemic circulation--the rat chylomicron remnants. Competition experiments between apo-E HDLc and rat chylomicron remnants indicate that the hepatic uptake mechanism for the two macromolecules is identical. Given that the recognition of apo-E HDLc is mediated by the E apoprotein and that the kinetic uptake properties of chylomicron remnants and apo-E HDLc are almost identical, it is probable that the E apoprotein is the major determinant responsible for hepatic chylomicron remnant recognition.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Apolipoproteins / metabolism*
  • Biological Transport
  • Chylomicrons / metabolism*
  • Dogs
  • Female
  • Kinetics
  • Lipoproteins, HDL / metabolism*
  • Liver / metabolism*
  • Lymph / metabolism
  • Perfusion
  • Rats
  • Receptors, Drug / metabolism*

Substances

  • Apolipoproteins
  • Chylomicrons
  • Lipoproteins, HDL
  • Receptors, Drug