MECHANISMS OF MAMMALIAN FERTILIZATION/POLYSPERMY BLOCK

在小鼠体内，一种名为ZP3的单一糖蛋白可以解释精子 小带的受体和顶体反应诱导活性 透明，这是围绕在卵子周围的一层细胞外衣。它是 认为受精刺激大脑皮层的胞吐作用 颗粒内容物，它改变了小带，使其精子 受体和顶体反应诱导活性丧失。 我们观察到分离的佛波酯处理的小带 卵子保留了精子受体的活性，但失去了这种能力 引发完全的顶体反应；佛波醇酯激活 蛋白激酶C到目前为止，还不可能检测到 ZP3的哪些部分参与了顶体反应。 用检测方法监测精子-小带相互作用和顶体 反应，并使用糖肽和肽图 过程中，我们将比较从 未经处理和佛波酯处理的鸡蛋，因为这些差异 可能反映了ZP3中涉及的那些部分 顶体反应。 因为我们已经证明了细胞的生化修饰 佛波酯处理的卵子中的小带与受精卵中的小带相似 鸡蛋，我们认为这些化合物刺激大脑皮层 颗粒反应。我们将通过以下特征来检验这一假设 分泌蛋的组成及其酶学性质 产品对佛波醇酯的响应，并将其与 电子引起的皮质颗粒数量减少 显微镜。 最后，我们将研究微量注射IP3和 鸟嘌呤核苷酸类似物在刺激早期事件中的作用 哺乳动物卵子的激活，因为这些化合物形成了一个信号 与蛋白激酶C结合的信号转导途径。 这些化合物在哺乳动物卵子激活事件中的作用 是未知的。 这些研究的结果将提供丰富的新信息 关于(1)ZP3介导的生化基础 顶体反应的诱导，(2)佛波醇酯 刺激皮质颗粒胞吐；这将提供 为进一步研究皮质颗粒提供便利的系统 反应，以及(3)肌醇磷脂周转的作用 途径，鸟嘌呤核苷酸、IP3和蛋白激酶C 激活剂在哺乳动物卵子的早期事件中起着核心作用。 激活。

In the mouse, a single glycoprotein, ZP3, accounts for sperm receptor and acrosome reaction inducing activities of the zona pellucia, which is an extracellular coat surrounding the egg. It is thought that fertilization stimulates exocytosis of the cortical granule contents, which modify the zona so that both its sperm receptor and acrosome reaction inducing activities are lost. We have observed that zonae isolated for phorbol ester-treated eggs retain their sperm receptor activity, but have lost the ability to induce a complete acrosome reaction; phorbol esters activate protein kinase C. To date, it has not been possible to examine what moieties of ZP3 are involved in the acrosome reaction. Using assays to monitor sperm-zona interaction and the acrosome reaciton, and employing glycopeptide and peptide mapping procedures, we will compare the properties of ZP3 isolated from untreated and phorbol ester-treated eggs, since these differences are likely to reflect those portions of ZP3 involved in the acrosome reaction. Since we have shown that the biochemical modification of the zona in phorbol ester-treated eggs is similar to that in fertilized eggs, we propose that these compounds stimulate the cortical granule reaction. We will test this hypothesis by characterizing the composition and enzymatic properties of secreted egg products in response to phorbol esters, and correlating this with a decrease in the number of cortical granules by electron microscopy. Lastly, we will examine the effects of microinjecting IP3 and guanine nucleotide analogs in stimulating early events of mammalian egg activation, since these compounds form a signal transduction pathway in conjunction with the protein kinase C. The role of these compounds in mammalian egg activation events is not known. Results of these studies will provide a wealth of new information regarding ( 1) the biochemical basis for the ZP3-mediated induction of the acrosome reaction, (2) how phorbol esters stimulate cortical granule exocytosis; this will provide a convenient system for future studies of the cortical granule reaction, and (3) the role of the phosphoinositide turnover pathway, of which guanine nucleotides, IP3, and protein kinase C activators play a central role, in early events of mammalian egg activation.