Windmueller H G, Herbert P N, Levy R I
J Lipid Res. 1973 Mar;14(2):215-23.
The ability of rat intestine and liver to synthesize the various apoproteins of plasma lipoproteins was investigated. After the individual isolated organs were perfused with blood containing [(3)H]lysine, chylomicrons plus very low density lipoproteins (VLDL), low density lipoproteins (LDL), and high density lipoproteins (HDL) were isolated from the perfusates and the intestinal lymph. After lipoprotein delipidation, apoproteins were separated by polyacrylamide gel electrophoresis and the (3)H content was determined. Livers incorporated [(3)H]lysine into all apoprotein bands of VLDL and HDL. The (3)H content was greater in large proteins that remained in the stacking gel (group I, predominantly beta-apoprotein) than in proteins with apparent molecular weights near 50,000 (group II) or in the smaller peptides (molecular weights near 10,000, group III). In the intestine, (3)H was incorporated into group I and, in larger amounts, into group II apoproteins of lymph VLDL. No labeled VLDL appeared in the perfusate. (3)H was also incorporated into group II apoproteins of lymph and perfusate HDL. Significantly, no [(3)H]lysine was found in the group III peptides of any lymph or intestinal perfusate lipoproteins. Since these peptides were always present in VLDL from mesenteric lymph collected in vivo, the results suggest that nascent VLDL of gut origin acquires group III peptides from other lipoproteins that penetrate lymph from plasma.
研究了大鼠肠道和肝脏合成血浆脂蛋白各种载脂蛋白的能力。用含[³H]赖氨酸的血液灌注分离出的各个器官后，从灌注液和肠淋巴中分离出乳糜微粒加极低密度脂蛋白（VLDL）、低密度脂蛋白（LDL）和高密度脂蛋白（HDL）。脂蛋白脱脂后，通过聚丙烯酰胺凝胶电泳分离载脂蛋白并测定³H含量。肝脏将[³H]赖氨酸掺入VLDL和HDL的所有载脂蛋白条带中。留在堆积凝胶中的大蛋白质（I组，主要是β-载脂蛋白）中的³H含量高于表观分子量接近50,000的蛋白质（II组）或较小的肽段（分子量接近10,000，III组）。在肠道中，³H掺入I组，并且大量掺入淋巴VLDL的II组载脂蛋白中。灌注液中未出现标记的VLDL。³H也掺入淋巴和灌注液HDL的II组载脂蛋白中。值得注意的是，在任何淋巴或肠灌注液脂蛋白的III组肽段中均未发现[³H]赖氨酸。由于这些肽段始终存在于体内收集的肠系膜淋巴的VLDL中，结果表明肠道来源的新生VLDL从其他从血浆渗入淋巴的脂蛋白中获得III组肽段。
