Vézina C A, Milne R W, Weech P K, Marcel Y L
Laboratory of Lipoprotein Metabolism, Clinical Research Institute of Montreal, Quebec.
J Lipid Res. 1988 May;29(5):573-85.
The heterogeneity of serum lipoproteins (excluding very low density (VLDL) and intermediate density (IDL) lipoproteins) and that of lipoproteins secreted by HepG2 cells has been studied by immunoblot analysis of the apolipoprotein composition of the particles separated by polyacrylamide gradient gel electrophoresis (GGE) under nondenaturing conditions. The reactions of antibodies to apoA-I, apoA-II, apoE, apoB, apoD, and apoA-IV have revealed discrete bands of particles which differ widely in size and apolipoprotein composition. GGE of native serum lipoproteins demonstrated that apoA-II is present in lipoproteins of limited size heterogeneity (apparent molecular mass 345,000 to 305,000) and that apoB is present in low density lipoproteins (LDL) and absent from all smaller or denser lipoproteins. In contrast, serum apoA-I, E, D, and A-IV are present in very heterogeneous particles. Serum apoA-I is present mainly in particles of 305 to 130 kDa where it is associated with apoA-II, and in decreasing order of immunoreactivity in particles of 130-90 kDa, 56 kDa, 815-345 kDa, and finally within the size range of LDL, all regions where there is little detectable apoA-II. Serum apoE is present in three defined fractions, one within the size range of LDL, one containing heterogeneous particles between 640 and 345 kDa, and one defined fraction at 96 kDa. Serum apoD is also present in three defined fractions, one comigrating with LDL, one containing heterogeneous particles between 390 and 150 kDa, and one band on the migration front. Most of serum apoA-IV is contained in a band comigrating with albumin. GGE of centrifugally prepared LDL shows the presence of apoB, apoE, and apoD, but not that of apoA-I. However, the particles containing apoA-I, which, in serum, migrated within the LDL size range and as bands of 815 to 345 kDa, were recovered upon centrifugation in the d greater than 1.21 g/ml fraction. GGE of high density lipoproteins (HDL) indicated that most of apoA-I, A-II, and A-IV were present in lipoproteins of the same apparent molecular mass (390-152 kDa). ApoD tended to be associated with large HDL, and this was also significant for HDL apoE, which is present in lipoproteins ranging from 640 to 275 kDa. GGE of very high density lipoproteins (VHDL) presented some striking features, one of which was the occurrence of apolipoproteins in very discrete bands of different molecular mass. ApoA-II was bimodally distributed at 250-175 kDa and 175-136 kDa, the latter fraction also containing apoA-I.(ABSTRACT TRUNCATED AT 400 WORDS)
通过对在非变性条件下经聚丙烯酰胺梯度凝胶电泳（GGE）分离的脂蛋白颗粒载脂蛋白组成进行免疫印迹分析，研究了血清脂蛋白（不包括极低密度脂蛋白（VLDL）和中间密度脂蛋白（IDL））以及HepG2细胞分泌的脂蛋白的异质性。针对载脂蛋白A-I、A-II、E、B、D和A-IV的抗体反应揭示了大小和载脂蛋白组成差异很大的颗粒离散条带。天然血清脂蛋白的GGE表明，载脂蛋白A-II存在于大小异质性有限的脂蛋白中（表观分子量345,000至305,000），载脂蛋白B存在于低密度脂蛋白（LDL）中，而在所有较小或较致密的脂蛋白中均不存在。相比之下，血清载脂蛋白A-I、E、D和A-IV存在于非常异质的颗粒中。血清载脂蛋白A-I主要存在于305至130 kDa的颗粒中，在该颗粒中它与载脂蛋白A-II相关，并且在130 - 90 kDa、56 kDa、815 - 345 kDa颗粒中的免疫反应性依次降低，最后在LDL大小范围内，所有这些区域中几乎检测不到载脂蛋白A-II。血清载脂蛋白E存在于三个明确的组分中，一个在LDL大小范围内，一个包含640至345 kDa之间的异质颗粒，另一个明确的组分在96 kDa处。血清载脂蛋白D也存在于三个明确的组分中，一个与LDL共迁移，一个包含390至150 kDa之间的异质颗粒，以及迁移前沿的一条带。血清载脂蛋白A-IV的大部分包含在与白蛋白共迁移的条带中。离心制备的LDL的GGE显示存在载脂蛋白B、E和D，但不存在载脂蛋白A-I。然而，含有载脂蛋白A-I的颗粒，在血清中其在LDL大小范围内迁移并呈815至345 kDa的条带，在密度大于1.21 g/ml的组分中离心后被回收。高密度脂蛋白（HDL）的GGE表明，大多数载脂蛋白A-I、A-II和A-IV存在于表观分子量相同的脂蛋白中（390 - 152 kDa）。载脂蛋白D倾向于与大的HDL相关，这对于HDL载脂蛋白E也很显著，HDL载脂蛋白E存在于640至275 kDa的脂蛋白中。极高密度脂蛋白（VHDL）的GGE呈现出一些显著特征，其中之一是载脂蛋白出现在不同分子量的非常离散的条带中。载脂蛋白A-II在250 - 175 kDa和175 - 136 kDa处呈双峰分布，后一组分也包含载脂蛋白A-I。（摘要截断于400字）
