LIPID DOMAINS IN THE YOLK LIPOPROTEIN COMPLEX *
LIPID DOMAINS IN THE YOLK LIPOPROTEIN COMPLEX *
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蛋黄脂蛋白复合物中的脂质结构域 *
DOI：
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发表时间：
1980
影响因子：
5.2
通讯作者：
L. Banaszak
中科院分区：
文献类型：
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作者：
Joe Ross;R. Wrenn;D. Ohlendorf;L. Banaszak
由于血清脂蛋白的大小和复杂性，人们对多种“模型”脂蛋白系统进行了研究，目的是了解其组织。一种这样的模型系统是在卵生动物的卵母细胞中发现的卵黄脂蛋白复合物。两栖动物卵中的卵黄系统以微晶形式存在，因此可以通过衍射方法进行研究。就蛋黄、血清和其他可溶性脂蛋白之间脂质和蛋白质的总体组装存在相似性而言，简单的有序模型系统可以提供丰富的结构数据。非洲爪蟾和其他两栖动物、鸟类和昆虫的卵黄系统含有两种主要成分：称为脂卵黄蛋白的脂蛋白和称为卵黄高磷蛋白的磷蛋白。该复合物源自肝脏中产生的称为脂卵黄素的前体蛋白。卵黄蛋白原在血清中以被认为含有分子量范围为180,000-200,000.2的单一多肽链的两个拷贝的形式转运。据信该单链多肽前体在被卵巢摄取期间被裂解成卵黄高磷蛋白和卵黄卵黄蛋白中的三种不同的多肽。对非洲爪蟾卵黄脂蛋白的生化分析，结合早期对其大小的估计，表明它是分子量为 456,000.4 的二聚体复合物。4 每个单体单元包含四种不同的多肽链，称为 LV-A (MW 105,000)、LV-B (MW 35,500) 和 LV-C (MW 32,000)。4 另一种蛋白质成分磷黄蛋白 (Phosvitin) 被发现可以分子量为17,000.4，该复合物含有约17%的脂质，经进一步分析，相当于lip~卵黄蛋白每个亚基中约35分子磷脂和15分子中性脂质的化学计量。
Because of the size and complexity of the serum lipoproteins, a variety of “model” lipid-protein systems have been studied with the goal of understanding their organization. One such model system is the yolk lipoprotein complex found in oocytes from oviparous animals. This yolk system in amphibian eggs is present in microcrystalline form,’ and hence can be studied by diffraction methods. To the extent that similarities exist in the overall assembly of lipid and protein between the yolk, serum, and other soluble lipoproteins, simple ordered model systems can propide a wealth of structural data. The yolk system from Xenopus laevis and other amphibia, birds, and insects contains two major components : a lipoprotein called lipovitellin and a phosphoprotein named phosvitin. This complex is derived from a precursor protein called lipovitellogenin, produced in the liver. Lipovitellogenin is transported in the serum in a form that is thought to contain two copies of a single polypeptide chain having a molecular weight in the range of 180,000-200,000.2~ This single chain polypeptide precursor is believed to be cleaved during uptake by the ovaries into phosvitin and the three different polypeptides in lipovitellin. Biochemical analysis of the yolk lipoprotein from Xenopus, combined with earlier estimates of its size, showed that it is a dimeric complex of MW 456,000.4 Each monomeric unit contains four different polypeptide chains called LV-A (MW 105,000), LV-B (MW 35,500), and LV-C (MW 32,000).4 Phosvitin, the other protein component, was found to have a molecular weight of 17,000.4 The complex contains about 17% lipid, which, by further analysis, is equivalent to a stoichiometry of about 35 molecules of phospholipid and 15 molecules of neutral lipid in each subunit of lip~vitellin.~