STRUCTURAL STUDIES OF LIPID:PROTEIN SYSTEMS

大分子结构将通过x射线结晶学和 这些数据将用于研究结构/功能关系 同时含有蛋白质和类脂的生物系统。几种不同的 蛋白质已经结晶并进行了部分分析。第一， 卵黄素是一种结合磷脂含量为-15%(w/w)的脂蛋白。 这个正在进行的项目因发现 卵黄蛋白的氨基酸序列与卵黄蛋白的氨基酸序列部分相关。 载脂蛋白100，一种与人血清低密度脂蛋白相关的蛋白质。低密度脂蛋白水平 与多种心血管疾病相关，尤其是 动脉硬化。第二个项目涉及脂肪的结构研究。 酸结合蛋白(FABP)。这些小蛋白是一种 更大的结构相似的分子家族，负责 脂肪酸或其他物质的胞内穿梭或胞外运输 不溶于水的配体。在一些细胞中，如脂肪细胞，调节 脂肪动员通过几种不同的机制发生。将出现一个 在胰岛素及其受体的影响下，涉及 脂肪细胞FABP的磷酸化。这可能是一种反应 调节脂肪组织中的脂肪动员。使用x射线分析， 重组肝脏和脂肪细胞FABP的结构将被确定。在一个 将蛋白质构象改变为具有 具有一定的催化酯酶活性。第三个项目涉及单项 另一种重组蛋白的晶体X射线研究 线粒体苹果酸脱氢酶。PremMDH是苹果酸的形式 在胞浆中生物合成的脱氢酶。被一些未知的人 它被内膜基质识别并转移到内膜基质的机制 线粒体。在这一点上，发生了蛋白质分解反应， 成熟形式的苹果酸脱氢酶(-22个来自NH2末端的氨基酸) 已经形成了。重要的生物学问题集中在结构上 这是识别和转移过程的基础。后者涉及 通过双层类脂。

Macromolecular structures will be obtained by x-ray crystallography and this data will be used to study structure/function relationships for biological systems containing both proteins and lipids. Several different proteins have already been crystallized and partially analyzed. The first, lipovitellin, is a lipoprotein containing -15% w/w of bound phospholipid. this ongoing project has taken on added interest with the discovery that the amino acid sequence of lipovitellin is in part related to that of apob100, a protein associated with human serum LDL. Levels of LDL correlate with a variety of cardiovascular diseases, particularly atherosclerosis. The second project involves structural studies of fatty acid binding proteins (FABPs). These small proteins are members of a larger family of structurally similar molecules responsible for either intracellular shuttling or extracellular transport of fatty acids or other water insoluble ligands. In some cells such as adipocytes, regulation of fat mobilization occurs through several different mechanisms. One appears to be under the influence of insulin and its receptor, and involves phosphorylation of adipocyte FABP. This may be the reaction which regulates lipid mobilization in fat tissue. Using x-ray analysis, the structure of recombinant liver and adipocyte FABP will be determined. In a related focussing of changing the protein conformation to a form which has some catalytic esterase activity. The third project involves single crystal x-ray studies of another recombinant protein, the precursor form of mitochondrial malate dehydrogenase, premMDH. PremMDH is the form of malate dehydrogenase which is biosynthesized in cytosol. By some unknown mechanism it is recognized by and translocated to the inner membrane matrix of mitochondria. At that point, a proteolytic reaction occurs and the mature form of malate dehydrogenase (-22 amino acids from the NH2-terminal) is formed. The important biological questions center on the structural basis for the recognition and translocation process. The latter involves passage through bilayer lipid.