Yamamoto T, Suda M, Moriwaki Y, Takahashi S, Higashino K
Third Department of Internal Medicine, Hyogo College of Medicine, Japan.
Biochim Biophys Acta. 1990 Oct 22;1047(1):49-56. doi: 10.1016/0005-2760(90)90259-z.
The apoprotein A-I (apo A-I)-containing lipoprotein (LPHuH-7apoA-I) was isolated from the concentrated conditioned medium of human hepatoma-derived cell line HuH-7 by immunoaffinity chromatography. LpHuH-7apoA-I consists of two kinds of lipoproteins. One is a lipoprotein of large particle size (LpL) with broad electrophoretic mobility on agarose gel ranging from the origin to the position of prebeta-lipoprotein. LpL is protein-rich in composition (protein, 75.4% by weight) and is heterogeneous in size (34-17 nm in diameter) electron microscopically. However, the most intriguing properties of LpL are its partial electrophoretic mobility towards the cathode on agar gel. The other lipoprotein is of small particle size (LpS). It demonstrates prebeta-electrophoretic mobility on agarose gel. LpS is also protein-rich in composition (protein, 95.4% by weight) and is heterogeneous in size (16.5-8.4 nm in diameter) electron microscopically. LpL is obviously different from LP-X and LP-Y in property, although LP-X, LP-Y and a part of LpL migrate towards the cathode on agar gel electrophoresis. LpS is also different from human apo A-I-containing lipoprotein without apo A-II in property, although these two lipoproteins possess the same mobility on agarose gel electrophoresis. These results indicate that both LpL and LpS are novel lipoproteins which have not yet been reported. The major isoproteins of the apo A-I of LpHuH-7apoA-I are apo A-I isoprotein 2 (apo A-I2), apo A-I isoprotein 4 (apo A-I4) and apo A-I isoprotein 5 (apo A-I5), and are different from those of apo A-I in human plasma and in the conditioned medium of hepatoma-derived cell line HepG2. This result suggests the presence of a proteinase which converts proapoprotein A-I (apo A-I2) to apoprotein A-I (apo A-I4) in the conditioned medium of HuH-7.
通过免疫亲和层析法从人肝癌衍生细胞系HuH-7的浓缩条件培养基中分离出含载脂蛋白A-I（apo A-I）的脂蛋白（LPHuH-7apoA-I）。LpHuH-7apoA-I由两种脂蛋白组成。一种是大颗粒脂蛋白（LpL），在琼脂糖凝胶上具有较宽的电泳迁移率，从原点到前β-脂蛋白的位置。LpL的组成富含蛋白质（蛋白质含量按重量计为75.4%），在电子显微镜下大小不均一（直径为34-17nm）。然而，LpL最引人注目的特性是其在琼脂凝胶上向阴极的部分电泳迁移率。另一种脂蛋白是小颗粒脂蛋白（LpS）。它在琼脂糖凝胶上显示前β-电泳迁移率。LpS的组成也富含蛋白质（蛋白质含量按重量计为95.4%），在电子显微镜下大小不均一（直径为16.5-8.4nm）。尽管LP-X、LP-Y和部分LpL在琼脂糖凝胶电泳中向阴极迁移，但LpL在性质上明显不同于LP-X和LP-Y。尽管这两种脂蛋白在琼脂糖凝胶电泳中具有相同的迁移率，但LpS在性质上也不同于不含apo A-II的人apo A-I含脂蛋白。这些结果表明LpL和LpS都是尚未见报道的新型脂蛋白。LpHuH-7apoA-I的apo A-I主要同工蛋白是apo A-I同工蛋白2（apo A-I2）、apo A-I同工蛋白4（apo A-I4）和apo A-I同工蛋白5（apo A-I5），与人类血浆和肝癌衍生细胞系HepG2条件培养基中的apo A-I不同。这一结果表明在HuH-7的条件培养基中存在一种蛋白酶，可将前载脂蛋白A-I（apo A-I2）转化为载脂蛋白A-I（apo A-I4）。
