Glycosylation of rat sperm plasma membrane during epididymal maturation.
Glycosylation of rat sperm plasma membrane during epididymal maturation.
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DOI：
10.1095/biolreprod48.2.417
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发表时间：
1993-02
影响因子：
3.6
通讯作者：
Daulat R. P. Tulsiani;M. Skudlarek;M. Holland;M. Orgebin‐Crist
中科院分区：
文献类型：
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作者：
Daulat R. P. Tulsiani;M. Skudlarek;M. Holland;M. Orgebin‐Crist
精子在通过附睾时获得受精能力。精子表面糖蛋白上寡糖部分的修饰是一些生化变化，据信在通过附睾期间对功能成熟的精子的产生很重要。为了了解这些修饰背后的机制，我们量化了附睾各个区域的精子和液体的四种糖基转移酶活性（催化糖残基从核苷酸糖供体转移到糖蛋白和糖脂上的糖链的酶）。我们的结果如下。 (1)只有总糖基转移酶活性(唾液酸转移酶、岩藻糖基转移酶、半乳糖基转移酶和N-乙酰氨基葡萄糖转移酶)的10-20%与精子一起沉积；其余 80-90% 的四种酶以可溶形式存在于附睾液中。 (2)当每10(6)个精子表达四种转移酶活性时，只有唾液酸转移酶和岩藻糖基转移酶活性表现出成熟依赖性变化。前一种酶在近端精子中显着较高，而后者在远端精子中显着较高。头状精子上两种酶的较高水平可能是由于它们与精子表面上的内源糖受体分子结合，并随后分别在近端和远端头状精子中的分子连续唾液酸化和岩藻糖基化后释放。 (3)当来自近端和远端头、体以及近端和远端尾部的精子与岩藻糖标记的核苷酸糖(GDP[14C]岩藻糖)一起孵育时，较高水平的放射性通常掺入来自远端头的精子中。 (4) [14C]岩藻糖标记的精子或精子质膜溶解后，在 SDS-PAGE 上解析，并通过放射自显影观察，表明放射性已掺入 86 kDa 的内源受体（主要成分）和几个次要成分中。用N-聚糖酶处理溶解的精子表明[14C]岩藻糖主要存在于N-连接寡糖单元上。这些研究表明，一些精子表面成分在精子成熟过程中发生岩藻糖基化。讨论了精子表面成分的体外岩藻糖基化在功能成熟精子产生中的潜在意义。
Spermatozoa acquire fertilizing ability during passage through the epididymis. Modification of oligosaccharide moieties on sperm surface glycoproteins are some of the biochemical changes believed to be important in the production of functionally mature spermatozoa during passage through the epididymis. In an attempt to understand the mechanism underlying these modifications, we quantified four glycosyltransferase activities (the enzymes that catalyze the transfer of sugar residues from nucleotide sugar donor to the sugar chains on glycoproteins and glycolipids) of spermatozoa and fluid from various regions of the epididymis. Our results are as follows. (1) Only 10-20% of the total glycosyltransferase activities (sialyltransferase, fucosyltransferase, galactosyltransferase, and N-acetyl glucosaminyltransferase) sedimented with the spermatozoa; the remaining 80-90% of the four enzymes were present in soluble form in the epididymal fluid. (2) When the four transferase activities were expressed per 10(6) spermatozoa, only sialyltransferase and fucosyltransferase activities showed maturation-dependent changes. The former enzyme was significantly higher on the proximal caput spermatozoa and the latter on the distal caput spermatozoa. The higher levels of the two enzymes on caput spermatozoa could be due to their binding to the endogenous sugar acceptor molecules on the sperm surface, and subsequent release following sequential sialylation and fucosylation of the molecules in the proximal and distal caput spermatozoa, respectively. (3) When spermatozoa from the proximal and distal caput, corpus, and proximal and distal cauda were incubated with fucose-labeled nucleotide sugar (GDP[14C]fucose), higher levels of radioactivity were routinely incorporated into the spermatozoa from the distal caput. (4) The [14C]fucose-labeled spermatozoa or sperm plasma membranes, when solubilized, resolved on SDS-PAGE, and visualized by autoradiography, showed that the radioactivity had been incorporated into an endogenous acceptor of 86 kDa (major component) and several minor components. Treatment of the solubilized spermatozoa with N-glycanase suggested that the [14C]fucose is mainly present on N-linked oligosaccharide units. These studies demonstrate that some of the sperm surface components are fucosylated during sperm maturation. The potential significance of the in vitro fucosylation of sperm surface components in the production of functionally mature spermatozoa is discussed.