GLUCOSYLTRANSFERASE IN MAMMARY GLAND

N-连接的糖蛋白的生物合成涉及到一个步骤，即二羟甲基-二羟甲基-2-羟基苯酚- 四糖前体Glc3Man9GlcNAc2及其En的连接组装 嵌段转移到新生多肽，然后是共翻译和翻译后 低聚糖部分的修饰。糖基的供体 前体中的残基是GLC-P-Dol；其生物合成是由 UDP-GLC：DOL-P葡萄糖基转移酶。已有研究表明，葡萄糖的糖基化 前体发出信号将其转移到受体多肽。一个人可以 假设葡萄糖转移酶的作用是关键的一步 对N-糖基化的整体调控。乳腺拥有 生物合成与调控研究的几个独特特点 糖蛋白。它的生长受到强烈的荷尔蒙调节， 发育在休眠-之间反复循环； 哺乳期-&gt；回归--&gt；休眠贯穿整个生殖生命 女性。此外，乳腺会合成并分泌大量 仅将有限数量的特性良好的糖蛋白 牛奶。我们实验室以前的研究已经阐明了 苯二醇环和中间体的立体化学结构 在乳腺中的循环。第一种酶，即UDP-GlcNAc：DOL- P-GlcNAc-1-P-转移酶和加工特异性葡萄糖苷酶I和II有 已经被提纯了。拟议的计划将提纯、表征和克隆 葡萄糖基转移酶。创新的方法论，基于综合 酶底物的新型类似物将被合并到 净化方案。将该酶基因克隆到原核表达系统中 载体为lambdaZAP-II。在这项工作范围之外的研究中，分子 葡萄糖基转移酶的探针将被用来研究腺体。 糖基化蛋白和糖基化蛋白表达的最新开创性研究 功能性糖蛋白tPA、α-抗胰蛋白酶和凝血因子 转基因动物乳汁中的IX说明了乳房的力量 腺体作为一种具有巨大潜力的生物医药和农用化学品生物反应器 目的。糖蛋白参与生物的广泛领域 功能和识别现象。病理状态包括 恶性肿瘤、动脉粥样硬化和许多常染色体隐性遗传病 并伴有细胞糖蛋白代谢的显著改变。一个 HIV gp120与CD4受体的糖蛋白-糖蛋白相互作用 在淋巴细胞上为病毒的传入提供了入口 遗传物质进入宿主导致艾滋病。

The biosynthesis of N-linked glycoproteins involves a step wise, dolichol- linked assembly of a tetrasaccharide precursor, Glc3Man9GlcNAc2 and its en bloc transfer to the nascent peptide followed by co- and post-translational modifications of the oligosaccharyl moiety. The donor for the glycosyl residues in the precursor is Glc-P-Dol; its biosynthesis is catalyzed by UDP-Glc:Dol-P glucosyltransferase. It has been shown that glucosylation of the precursor signals its transfer to the acceptor polypeptides. One may hypothesize that the action of glucosyltransferase represents a key step for the overall regulation of N-glycosylation. The mammary gland possesses some unique features for studying the biosynthesis and regulation of glycoproteins. It is under intense hormonal modulation for its growth and development as it repeatedly cycles between dormancy -> gestation -> lactation -> regression -> dormancy throughout the reproductive life of the female. Further, the lactating gland synthesizes and secretes massive amounts of only a limited number of well characterized glycoproteins into milk. Previous studies from our laboratory have elucidated the outlines of the dolichol cycle and the stereochemical structures of the intermediates of the cycle in the mammary gland. The first enzyme, i.e., UDP-GlcNAc:Dol- P GlcNAc-1-P-transferase and processing-specific glucosidases I and II have been purified. The proposed program will purify, characterize and clone the glucosyltransferase. Innovative methodologies, based on the synthesis of novel analogs of the enzyme substrate will be incorporated in the purification protocol. The enzyme cDNA will be cloned in the expression vector lambdaZAP-II. IN studies outside the scope of this work, molecular probes for glucosyltransferase will be employed to investigate the gland. The recent pioneering studies on the expression of glycosylated and functional glycoproteins tPA, alpha-antitrypsin and blood clotting factor IX in the milk of transgenic animals illustrate the power of the mammary gland as a bioreactor of immense potential for biomedical and agrochemical purposes. Glycoproteins participate in a wide spectrum of biological functions and recognition phenomena. Pathological states including malignancy, atherosclerosis and many autosomal recessive disorders are accompanied with marked alterations in cellular glycoprotein metabolism. A glycoprotein-glycoprotein interaction between gp120 of HIV and CD4 receptor on the lymphocyte provides the entry port for the introduction of viral genetic material into the host leading to AIDS.