Role of luminal fluid glycosyltransferases and glycosidases in the modification of rat sperm plasma membrane glycoproteins during epididymal maturation.
Role of luminal fluid glycosyltransferases and glycosidases in the modification of rat sperm plasma membrane glycoproteins during epididymal maturation.
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发表时间：
1998
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通讯作者：
D. Tulsiani;M. Orgebin‐Crist;M. Skudlarek
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作者：
D. Tulsiani;M. Orgebin‐Crist;M. Skudlarek
哺乳动物精子在附睾运输过程中发生生化和形态学变化，统称为附睾成熟。虽然生化修饰的许多细节还没有完全了解，凝集素结合的研究，从几个实验室强烈建议，精子质膜糖蛋白的聚糖部分被广泛修改为精子从近端到远端附睾过境。在本文中，我们总结了我们的研究与两套聚糖修饰酶，即糖基转移酶（合成酶）和glycoproteinases（水解酶）在大鼠精子收集从不同地区的附睾，和类似的酶活性存在于附睾腔液。结果表明，这些酶在附睾腔液中的活性较高（血浆中酶活性占总酶活性的80%以上）。本报告中提出的证据还表明：（1）至少一种精子表面糖蛋白当头部精子与GDP [14 C]岩藻糖孵育时，（表观分子量为86 kDa）在体外被岩藻糖基化;（2）存在于精子质膜上的花生凝集素（PNA）阳性糖蛋白，分子量为135-150 kDa通过用纯化的腔液β-D-半乳糖苷酶消化，使附睾（而不是尾部）去半乳糖基化。两者合计，这些结果强烈建议在附睾成熟过程中的精子表面糖蛋白的修饰糖蛋白修饰酶的作用。
It is generally accepted that mammalian spermatozoa undergo biochemical and morphological changes during epididymal transit, collectively termed epididymal maturation. Although many details of the biochemical modification are not fully understood, lectin binding studies from several laboratories strongly suggest that glycan moieties of sperm plasma membrane glycoproteins are extensively modified as spermatozoa transit from the proximal to the distal epididymis. In the present article, we summarize our studies with two sets of glycan modifying enzymes, namely glycosyltransferases (synthetic enzymes) and glycosidases (hydrolytic enzymes) in rat spermatozoa collected from different regions of the epididymis, and similar enzyme activities present in the epididymal luminal fluid. Our data show that the activities of these enzyme are high in the epididymal luminal fluid (> 80% of the total enzyme activities was in the plasma). Evidence presented in this report also demonstrates that: (1) at least one sperm surface glycoprotein (apparent molecular mass of 86 kDa) is fucosylated in vitro when caput spermatozoa are incubated with GDP [14C]fucose; and (2) a peanut agglutinin (PNA)-positive glycoprotein of 135-150 kDa present on plasma membrane of sperm from the caput (but not cauda) epididymidis is degalactosylated by digestion with purified luminal fluid beta-D-galactosidase. Taken together, these results strongly suggest a role for glycoprotein modifying enzymes in the modification of sperm surface glycoproteins during epididymal maturation.