MAMMALIAN SPERM SURFACE MANNOSIDASE

这个项目的重点是精子的生化特性 表面甘露糖苷酶，一种被认为在以下方面具有受体样作用的糖水解酶： 精卵相互作用及其对大鼠精子膜上糖链的影响 透明的该酶是一种内在的质膜（PM）蛋白，其 催化结构域朝向完整精子的外表面。 由于该酶在接近中性pH时具有最佳活性，因此它在功能上是 在体外和体内受精的生理环境中具有活性。的 PI已经证明：a）前体和成熟形式的存在， 睾丸PM和头部精子中的α-D-甘露糖苷酶 和Corpus。只有成熟的形式存在于尾部精子PM中; B） 酶在大鼠体内合成并部分加工成成熟形式 睾丸生殖细胞; c）蛋白质结合的糖残基在睾丸生殖细胞中的作用; 诱导精子的顶体反应; d）克隆和 大鼠ZP糖缀合物的表征;和e）功能意义 大鼠精子表面的甘露糖苷酶。本申请的目的是 继续进行中的研究。第一个目的是检查 生物合成，蛋白水解加工，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。 第二个目的是为了获得证据的存在， 大鼠ZP糖蛋白上的生物活性聚糖单位。第三个目的是检查 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研究人员长期研究的一部分， 目的是鉴定和化学表征互补分子 启动精卵相互作用的相对配子的表面。这 该项目将检查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以下信息： 精子表面甘露糖苷酶在卵子粘附和精子激活中的作用 在大鼠受精过程中， 这是在生物多样性期间观察到的高度物种特异性的基础。 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.