POTENTIAL ROLE FOR HEXOKINASE IN SPERM/EGG INTERACTION

哺乳动物受精的初始事件是 有受精能力的雄性和雌性配子（精子和卵子， 分别）。在精子发生和附睾成熟过程中， 精子的质膜变得能够结合到 卵的细胞外基质，透明细胞。这个精卵 相互作用是物种特异性的，并导致顶体的诱导 这是最终成功受精所需的反应。这些 相互作用具有配体-受体-效应物的许多特征 它们之间的相互作用调节着许多体细胞功能。而 与精子质膜结合的透明膜成分已经被 被证明是一种名为ZP 3的卵子特异性糖蛋白， 精子膜仍然未知。许多候选ZP 3受体具有 有人建议，包括一个主要的磷酸酪氨酸蛋白质的先生 95,000.最近，这种蛋白质已被纯化，并显示是一种独特的蛋白质。 糖酵解酶的膜结合的酪氨酸磷酸化形式 己糖激酶克隆研究的结果表明，精子可能含有 多种形式的己糖激酶，其中一些类似于体细胞 形式，其中一些似乎是生精细胞所特有的。的 这项建议的长期目标是检查这种己糖激酶是否 在精卵相互作用中起作用。具体目标是：1） 确定成熟精子中存在哪种己糖激酶亚型， 它的位置;特别是，是否有任何亚型定位于精子 膜覆盖顶体，精子-卵子相互作用的位点，2） 确定哪种己糖激酶亚型在酪氨酸上被磷酸化 成熟精子中的残留物及其成为 磷酸化，即自磷酸化事件和/或通过 酪氨酸激酶，以及3）确定成熟精子中的己糖激酶 参与精子-透明质酸相互作用;具体地，可以 这种相互作用可以用干扰己糖激酶的探针来抑制。 在健康方面，这些实验的结果将促进 对精卵结合和相互作用有更深入的了解。而且这些 实验可能会导致新的避孕方法， 了解不孕症的具体形式。

The initial event of mammalian fertilization is the interaction of fertilization-competent male and female gametes (the sperm and egg, respectively). During spermatogenesis and epididymal maturation, the plasma membrane of the sperm becomes capable of binding to the extracellular matrix of the egg, the zona pellucida. This sperm-egg interaction is species-specific and leads to the induction of the acrosome reaction which is ultimately required for successful fertilization. These interactions have many characteristics of ligand-receptor-effector interactions which regulate numerous somatic cell functions. While the zona pellucida component that binds to the sperm plasma membrane has been shown to be an egg-specific glycoprotein called ZP3, the receptor on the sperm membrane remains unknown. A number of candidate ZP3 receptors have been suggested including a major phosphotyrosine-containing protein of Mr 95,000. Recently, this protein has been purified and shown to be a unique membrane-bound, tyrosine-phosphorylated form of the glycolytic enzyme hexokinase. Results of cloning studies suggest that sperm may contain multiple forms of hexokinase, some of which are similar to the somatic forms and some of which appear to be unique to spermatogenic cells. The long-term objective of this-proposal is to examine whether this hexokinase in sperm has a role in sperm-egg interaction. The specific aims are: 1) to determine which isoform(s) of hexokinase is present in mature sperm and its location; specifically, whether any isoform localizes to the sperm membrane overlying the acrosome, the site of sperm-egg interaction, 2) to determine which isoform(s) of hexokinase is phosphorylated on tyrosine residues in the mature sperm and the mechanism by which it becomes phosphorylated, i.e. an autophosphorylation event and/or by the action of a tyrosine kinase, and 3) to determine whether hexokinase in mature sperm participates in the sperm-zona pellucida interaction; specifically, can this interaction be inhibited with probes that interfere with hexokinase. In relation to health the results from these experiments will promote a deeper understanding of sperm-egg binding and interaction. Moreover, these experiments may lead to new approaches to contraception and to a comprehension of specific forms of infertility.