MAMMALIAN SPERM SURFACE MANNOSIDASE

这个项目的重点是精子的生物化学特性。 表面甘露糖苷酶，一种糖水解酶，被认为在 精子-卵子相互作用及其在大鼠卵透明带上的互补糖链单位 透明质膜。该酶是一种固有的质膜(PM)蛋白，其 催化结构域定位于完整精子的外表面。 由于该酶在中性pH附近具有最佳活性，因此它在功能上 在体外和体内受精过程中活跃在生理环境中。这个 PI已经证明：a)存在先驱者和成熟形式的 睾丸精浆和头精子中的α-D-甘露糖苷酶 和语料库。只有成熟的形式存在于尾部精子PM中；b) 在大鼠体内合成酶并部分加工成成熟型 睾丸生殖细胞；c)蛋白质结合糖残基在睾丸发育中的作用 精子顶体反应的诱导；d)克隆和 大鼠ZP糖偶联物的特性；以及e)其功能意义 大鼠精子表面甘露糖苷酶。此应用程序的目标是 继续进行中的研究。第一个目标是为了检查 生物合成、蛋白质分解加工、细胞内运输和细胞 精子甘露糖苷酶在培养的生精细胞中的表面表达。 第二个目标是获得证据，证明存在补充性 大鼠ZP糖蛋白上的生物活性糖链单位。第三个目标是检查 多聚糖在精子-卵子相互作用中的功能意义 精子激活。拟议的研究是调查人员长期研究的一部分 目标鉴定和化学性质的互补分子从 启动精子-卵子相互作用的相对配子的表面。这 该项目将检查其中一个受体和配体部分据信是 参与受精。这些研究的数据将提供关于 精子表面甘露糖苷酶在卵子黏附和精子激活中的作用 在大鼠的受精过程中，将提供对机制的洞察 在此期间观察到的高度物种专一性 受精过程。

This project focuses on the biochemical characterization of sperm surface mannosidase, a glycohydrolase believed to have a receptor-like role in sperm-egg interaction and on its complimentary glycan units on rat zona pellucida. The enzyme is an intrinsic plasma membrane (PM) protein with its catalytic domain oriented towards the outer surface of the intact spermatozoa. Since the enzyme is optimally active near neutral pH, it would be functionally active in physiological settings during in vitro and in vivo fertilization. The PI has demonstrated: a) the presence of the precursor and mature forms of alpha-D-mannosidase in PMs from the testis and on spermatozoa from the caput and corpus. Only the mature form is present in the cauda sperm PM; b) that the enzyme is synthesized and partially processed to the mature form in rat testicular germ cells; c) the role of protein-conjugated sugar residues in the induction of the acrosome reaction of spermatozoa; d) the cloning and characterization of rat ZP glycoconjugates; and e) the functional significance of the rat sperm surface mannosidase. The aims of this application are a continuation of ongoing studies. The first aim is designed to examine biosynthesis, proteolytic processing, intracellular trafficking, and cell surface expression of the sperm mannosidase in spermatogenic cells in culture. The second aim is to obtain evidence for the presence of complementary bioactive glycan units on rat ZP glycoproteins. The third aim is to examine the functional significance of the glycans in the sperm-egg interaction and in sperm activation. The proposed studies are part of the investigators' long-term goal to identify and chemically characterize the complementary molecules from the surface of opposite gametes which initiate sperm-egg interaction. This project will examine one of the receptor and ligand moieties believed to be involved in fertilization. Data from these studies will provide information on the role of the sperm surface mannosidase in egg adhesion and sperm activation during fertilization in the rat and will provide insight into mechanisms underlying the high degree of species-specificity observed during the fertilization process.