Sherrill B C, Innerarity T L, Mahley R W
J Biol Chem. 1980 Mar 10;255(5):1804-7.
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.
仅含E载脂蛋白的犬脂蛋白（载脂蛋白E高密度脂蛋白，apo-E HDLc）经大鼠肝脏灌注时，表现出高亲和力、受体介导的摄取及饱和动力学。这些数据表明，apo-E HDLc的肝脏摄取是通过有限数量的结合位点进行的。在单次通过大鼠肝脏灌注期间测定的apo-E HDLc结合和摄取的动力学值为：Km = 4.99微克蛋白质·ml⁻¹，Vmax = 6.42微克蛋白质·g⁻¹·min⁻¹。以摩尔为基础，apo-E HDLc的肝脏提取几乎等同于从体循环中最迅速清除的一类脂蛋白——大鼠乳糜微粒残余物的高肝脏提取。apo-E HDLc与大鼠乳糜微粒残余物之间的竞争实验表明，这两种大分子的肝脏摄取机制相同。鉴于apo-E HDLc的识别是由E载脂蛋白介导的，且乳糜微粒残余物和apo-E HDLc的动力学摄取特性几乎相同，E载脂蛋白很可能是负责肝脏识别乳糜微粒残余物的主要决定因素。
