Dicalcin Inhibits Fertilization through Its Binding to a Glycoprotein in the Egg Envelope in Xenopus laevis
Dicalcin Inhibits Fertilization through Its Binding to a Glycoprotein in the Egg Envelope in Xenopus laevis
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DOI：
10.1074/jbc.m109.079483
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发表时间：
2010-05-14
影响因子：
4.8
通讯作者：
Kawamura, Satoru
中科院分区：
文献类型：
--
作者：
Miwa, Naofumi;Ogawa, Motoyuki;Kawamura, Satoru
受精包括寡糖介导的精卵相互作用，包括精子结合到细胞外卵包膜，精子穿透包膜，以及与卵质膜融合。我们发现，非洲爪蟾双钙蛋白，S100样钙结合蛋白，存在于细胞外卵包膜（卵黄包膜（VE）），是一种抑制性介质的精卵相互作用。用特异性抗体预孵育大大提高了体外受精的效率，而外源性二钙素的预先应用基本上抑制受精以及精子与卵子的结合和体外精子穿透VE蛋白层。Dicalcin表现出结合蛋白核心的GP41和GP37，成分VE，在一个Ca 2+依赖的方式和增加在体内的反应VE与凝集素，蓖麻凝集素I，这是占由GP41的凝集素和更大的接触GP41的外部环境的结合能力增加。我们的研究结果强烈表明，dicalcin通过其结合到gp41的蛋白质核心，可能通过调节gp41上的寡糖的构型和VE框架的三维结构来调节VE内寡糖的分布，从而在受精过程中精卵相互作用中起着关键作用。
Fertilization comprises oligosaccharide-mediated sperm-egg interactions, including sperm binding to an extracellular egg envelope, sperm penetration through the envelope, and fusion with an egg plasma membrane. We show that Xenopus dicalcin, an S100-like Ca2+-binding protein, present in the extracellular egg envelope (vitelline envelope (VE)), is a suppressive mediator of sperm-egg interaction. Preincubation with specific antibody greatly increased the efficiency of in vitro fertilization, whereas prior application of exogenous dicalcin substantially inhibited fertilization as well as sperm binding to an egg and in vitro sperm penetration through the VE protein layer. Dicalcin showed binding to protein cores of gp41 and gp37, constituents of VE, in a Ca2+-dependent manner and increased in vivo reactivity of VE with a lectin, Ricinus communis agglutinin I, which was accounted for by increased binding ability of gp41 to the lectin and greater exposure of gp41 to an external environment. Our findings strongly suggest that dicalcin regulates the distribution of oligosaccharides within the VE through its binding to the protein core of gp41, probably by modulating configuration of oligosaccharides on gp41 and the three-dimensional structure of VE framework, and thereby plays a pivotal role in sperm-egg interactions during fertilization.