MEMBRANE GLYCOPROTEIN CHANGES DURING DIFFERENTIATION

在雌激素诱导鸡输卵管分化过程中， 膜制备物中的多萜醇磷酸（Dol-P）和多萜醇激酶水平 似乎在增加。 调节Dol-P水平的机制将是 研究了 因此，我们计划研究参与Dol-P的异戊二烯基转移酶 由焦磷酸法呢酯和焦磷酸异戊烯酯合成 酶的性质及其在生长过程中可能的调节 分化 Dol-P的α-异戊二烯单元的比还原 将被研究。 我们还将研究其他可能参与 各种多萜醇衍生物的相互转化; Dol-P磷酸酶， 多萜醇：磷脂酰胆碱转酰酶和脂肪酰多萜醇酰化酶。 输卵管组织切片将与放射性甲羟戊酸和乙酸一起孵育 以确定各种长萜醇衍生物的合成速率， 胆固醇在输卵管分化和萎缩过程中的作用。 这些 研究还将使我们能够测量Dol-P的周转率和分布， 在其各种代谢形式中。 将研究脂质中间体途径各个步骤的变化 其中放射性脂质中间体外源性地加入到膜制剂中。 脂质连接寡糖、葡糖苷酶和甘露糖苷酶的组装 低聚糖加工中所涉及的问题是本研究的主题。 参与合成“复杂”糖蛋白的糖基转移酶也将 被研究。 将制备特异性糖蛋白底物，并转移 将分析来自糖核苷酸的糖。 输卵管含有β-N-乙酰葡萄糖苷酶和卵清白色两种同工酶 含有一种可能与输卵管同工酶相同的形式。 的 它们之间结构关系和可能的生物合成关系 将研究同工酶。 这些研究可能揭示了一些深刻的差异 胞内同工酶和分泌同工酶之间的差异。

During the course of estrogen induced chick oviduct differentiation dolichylphosphate (Dol-P) and dolichol kinase levels in membrane preparations appear to increase. The mechanisms by which Dol-P levels are modulated will be studied. Thus, we plan to study the prenyl transferases involved in Dol-P synthesis from farnesyl pyrophosphate and isopentenyl pyrophosphate with respect to the properties of the enzyme and its possible regulation during differentiation. The specific reduction of the alpha-isoprene unit of Dol-P will be studied. We will also study other enzymes that may be involved in the interconversion of various dolichol derivatives; Dol-P phosphatase, dolichol:phosphatidylcholine transacylase and fatty acyl dolichol acylase. Oviduct tissue slices will be incubated with radioactive mevalonate and acetate to determine the rates of synthesis of various dolichol derivatives and cholesterol during the course of oviduct differentiation and atrophy. These studies will also allow us to measure the turnover of Dol-P and the distribution of dolichol amongst its various metabolic forms. Changes in individual steps of the lipid intermediate pathway will be studied with radioactive lipid intermediates added exogenously to membrane preparations. Assembly of the lipid-linked-oligosaccharide, the glucosidases and mannosidases involved in oligosaccharide processing are the topics for this study. Glycosyl transferases involved in synthesizing "complex" glycoproteins will also be studied. Specific glycoprotein substrates will be prepared and transfer of sugar from sugar nucleotides will be assayed. The oviduct contains two isozymes of beta-N-acetylglucosamidase and egg white contains one form that may be identical to one of the oviduct isozymes. The structural relationships and possible biosynthetic relationship between these isozymes will be studied. These studies may reveal some profound differences between intracellular and secreted isozymes.