Dissociation of lipid-free apolipoprotein A-I from high density lipoproteins.
Dissociation of lipid-free apolipoprotein A-I from high density lipoproteins.
复制标题
无脂载脂蛋白 A-I 与高密度脂蛋白的解离。
作者：
H. Liang;K. Rye;P. Barter
本文研究了载脂蛋白A-I与人高密度脂蛋白（HDL）在体外孵育过程中的解离条件。通过非变性梯度凝胶电泳，然后通过apoA-I的免疫印迹和尺寸排阻色谱法证明apoA-I的解离。超离心后定量为d < 1.25 μ g/ml级分中apoA-I的损失。ApoA-I与HDL在37 ℃单独孵育24 h后，未发生解离。也没有解离的apoA-I的HDL孵育时，无论是与胆固醇酯转移蛋白（CETP）在没有其他脂蛋白组分或与其他脂蛋白在没有CETP。然而，当HDL和CETP的混合物在生理浓度的极低密度脂蛋白（VLDL）或低密度脂蛋白（LDL）的存在下孵育24小时时，有高达36%的apoA-I从HDL组分的解离，与时间呈线性关系。apoA-I的解离与HDL颗粒尺寸的时间依赖性减小相一致。apoA-I与HDL的解离百分率与VLDL、LDL、CETP浓度呈正相关，与HDL浓度呈负相关。当卵磷脂：胆固醇酰基转移酶加入到与CETP孵育24小时的混合物中时，HDL的大小增加，解离的apoA-I恢复到d < 1.25 μ g/ml的部分。对通过超离心分离的d > 1.25 μ g/ml的脂蛋白缺乏级分和在尺寸排阻色谱后回收的较低分子量级分的分析表明，解离的apoA-I与显著量的胆固醇、磷脂或其它载脂蛋白不相关。当解离的apoA-I进行琼脂糖凝胶电泳时，它迁移到与纯化的无脂质apoA-I相当的prebeta位置。这与表现出α迁移的原始HDL形成鲜明对比。因此，CETP介导的胆固醇酯从HDL向VLDL和LDL的转移不仅伴随着HDL大小的减少，而且伴随着前β-迁移的基本上无脂质的apoA-I池从HDL的逐步解离。
Conditions under which apolipoprotein (apo) A-I dissociates from human high density lipoproteins (HDL) during incubation in vitro have been investigated. Dissociation of apoA-I was demonstrated by non-denaturing gradient gel electrophoresis followed by immunoblotting for apoA-I and by size-exclusion chromatography. It was quantitated after ultracentrifugation as the loss of apoA-I from the fraction of d < 1.25 g/ml. ApoA-I did not dissociate from HDL when they were incubated alone at 37 degrees C for up to 24 h. Nor was there dissociation of apoA-I when the HDL were incubated either with the cholesteryl ester transfer protein (CETP) in the absence of other lipoprotein fractions or with other lipoproteins in the absence of CETP. However, when mixtures of HDL and CETP were incubated for 24 h in the presence of physiological concentrations of either very low density lipoproteins (VLDL) or low density lipoproteins (LDL), there was a dissociation of up to 36% of the apoA-I from the HDL fraction that was linear with time. The dissociation of apoA-I coincided with a time-dependent reduction in HDL particle size. The percentage of apoA-I that dissociated from HDL correlated positively with the concentrations of VLDL, LDL, and CETP in the incubation but negatively with the concentration of HDL. When lecithin:cholesterol acyltransferase was added to mixtures at the completion of 24 h of incubation with CETP, the size of the HDL increased and the dissociated apoA-I returned to the fraction of d < 1.25 g/ml. analysis of the lipoprotein-deficient fraction of d > 1.25 g/ml isolated by ultracentrifugation and of the lower molecular weight fractions recovered after size-exclusion chromatography revealed that the dissociated apoA-I was not associated with significant quantities of either cholesterol, phospholipids, or other apolipoproteins. When the dissociated apoA-I was subjected to agarose gel electrophoresis, it migrated to a prebeta position comparable to that of purified, lipid-free apoA-I. This contrasted with the original HDL that exhibited alpha migration. Thus, CETP-mediated transfers of cholesteryl esters from HDL to VLDL and LDL are accompanied not only by a reduction in HDL size but also by the progressive dissociation from HDL of a pool of prebeta-migrating, essentially lipid-free apoA-I.
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DOI：
10.1016/0026-0495(85)90027-7
发表时间：
1985
期刊：
Metabolism: clinical and experimental
影响因子：
--
作者：
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DOI：
10.1016/0005-2760(81)90253-8
发表时间：
1981-01-01
期刊：
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影响因子：
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作者：
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通讯作者：
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影响因子：
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通讯作者：
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影响因子：
6.5
作者：
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通讯作者：
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