Yonezawa N, Amari S, Takahashi K, Ikeda K, Imai F L, Kanai S, Kikuchi K, Nakano M
Graduate School of Science and Technology, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba-shi, Chiba 163-8522, Japan.
Mol Reprod Dev. 2005 Feb;70(2):222-7. doi: 10.1002/mrd.20195.
The zona pellucida (ZP) surrounding the mammalian oocyte is composed of three glycoprotein components (ZPA, ZPB, and ZPC). Mammalian sperm bind to carbohydrate chains of a ZP glycoprotein in the initial phase of fertilization. Sperm-ligand carbohydrate chains have been characterized in mouse, cow, and pig. In pigs, triantennary/tetraantennary neutral complex-type chains from ZPB/ZPC mixture possess stronger sperm-binding activity than those of biantennary chains (Kudo et al., 1998: Eur J Biochem 252:492-499). Most of these oligosaccharides have beta-galactosyl residues at the nonreducing ends. This study used two in vitro competition assays to investigate the participation of the nonreducing terminal beta-galactosyl residues of the ligand active chains in porcine sperm binding. The removal of the nonreducing terminal beta-galactosyl residues from either the ligand active carbohydrate chains or endo-beta-galactosidase-digested glycoproteins significantly reduced their inhibition of sperm-egg binding, indicating that the beta-galactosyl residues at the nonreducing ends are involved in porcine sperm-egg binding. A correlation between the sperm-binding activity and in vitro fertilization rate is also presented.
围绕哺乳动物卵母细胞的透明带（ZP）由三种糖蛋白成分（ZPA、ZPB和ZPC）组成。在受精初始阶段，哺乳动物精子会与ZP糖蛋白的碳水化合物链结合。在小鼠、牛和猪中，精子配体碳水化合物链已得到表征。在猪中，来自ZPB/ZPC混合物的三触角/四触角中性复合型链比双触角链具有更强的精子结合活性（Kudo等人，1998年：《欧洲生物化学杂志》252:492 - 499）。这些寡糖中的大多数在非还原端具有β - 半乳糖基残基。本研究使用两种体外竞争试验来研究配体活性链的非还原端β - 半乳糖基残基在猪精子结合中的作用。从配体活性碳水化合物链或经内切β - 半乳糖苷酶消化的糖蛋白中去除非还原端β - 半乳糖基残基，会显著降低它们对精卵结合的抑制作用，这表明非还原端的β - 半乳糖基残基参与了猪的精卵结合。同时还呈现了精子结合活性与体外受精率之间的相关性。
