OXYSTEROL BINDING PROTEIN AND CHOLESTEROL METABOLISM

胆固醇的新陈代谢是健康和疾病的中心问题。 氧化甾醇是已知的最有效的胆固醇合成调节剂。 它们是在类固醇生物合成的不同步骤中自然产生的 降解途径，它们很容易通过自氧化形成 身体和身体外面。 一种含有特定氧固醇结合位点的蛋白质组分已经被 最近在许多细胞和组织中发现。我们建议这一点 蛋白质组分含有一种特定的氧固醇结合蛋白(OBP)。 强效含氧甾醇对胞质结合部位的占据作用 在浓度和特异性方面，都与那些 能下调3-羟基-3-甲基戊二酰辅酶A的化合物 还原酶(HMG CoA还原酶)，胆固醇中的限速酶 生物合成。OBP的占有率也可能与细胞抑制有关 成长。因此，OBP可能是两者中重要的调节蛋白。 甾醇合成和细胞生长。 我们建议从人(CEM)细胞系和培养的细胞中提纯OBP 小鼠L细胞，制备抗它的单抗和多克隆抗体， 并利用这些来进一步研究蛋白质并进行分离和测序 它的基因。 我们还将确定特定和非特定的DNA结合属性 OBP的。来自几个来源的总基因组DNA和来自特定来源的DNA 基因，包括来自HMG CoA还原酶的基因，将被检查 有约束力的。

The metabolism of cholesterol is a central problem in health and disease. Oxysterols are the most potent known regulators of cholesterol synthesis. They are produced naturally at various steps in steroid biosynthetic and degradative pathways, and they are readily formed through autooxidation in the body and outside it. A protein fraction containing a specific oxysterol binding site has been identified recently in many cells and tissues. We propose that this protein fraction contains a specific oxysterol binding protein (OBP). Occupancy of this cytoplasmic binding site by potent oxygenated sterols correlates, both with respect toconcentration and specificity, with those compounds capable of down-regulating 3-hydroxy-3-methyglutary1 coenzyme A reductase (HMG CoA reductase), the rate limiting enzyme in cholesterol biosynthesis. Occupancy of OBP also may correlate with inhibition of cell growth. OBP may be, therefore, an important regulatory protein in both sterol synthesis and cell growth. We propose to purify OBP from a human (CEM) cell line and from cultured mouse L cells, to prepare both mono- and poly-clonal antibodies against it, and to use these to further study the protein and to isolate and sequence its gene. We also will determine the specific and non-specific DNA binding properties of OBP. Total genomic DNA from several sources, and DNA from specific genes, including the gene from HMG CoA reductase, will be examined for binding.