Parrington J, Lai F A, Swann K
Department of Anatomy and Developmental Biology University College, London, United Kingdom.
Curr Top Dev Biol. 1998;39:215-43. doi: 10.1016/s0070-2153(08)60457-3.
At fertilization in all species studied the sperm activates the egg by causing an increase in the level of cytoplasmic free Ca2+ concentration. It is still not established how the sperm causes the changes in Ca2+ in the egg, which in the majority of eggs is due to release from internal stores. Current hypotheses about the signaling molecules involved in fertilization are confounded by the fact that for many eggs the fertilization-associated Ca2+ increase is readily mimicked by parthenogenetic activating agents. One exception to this is found for mammalian eggs where there are a series of Ca2+ oscillations observed at fertilization that have distinct characteristics. In this context we discuss three different theories of how sperm trigger Ca2+ release in eggs. We present the case that the sperm mediates its Ca2+ mobilization effects after gamete membrane fusion by introducing a specific protein into the egg cytoplasm. Our argument is based upon the fact that only the mammalian sperm protein factor can trigger a pattern of Ca2+ oscillations that is similar to that induced by the sperm in mammalian eggs. The sperm factor activity is correlated with a novel signaling protein that we have called oscillin and which may mediate Ca2+ release via a novel mechanism.
在所有已研究的物种中，受精时精子通过使细胞质游离钙离子（Ca2+）浓度水平升高来激活卵子。目前仍未确定精子如何引起卵子中Ca2+的变化，在大多数卵子中，这种变化是由于内部储存库的释放。关于受精过程中涉及的信号分子的当前假说因以下事实而混淆：对于许多卵子，孤雌生殖激活剂很容易模拟与受精相关的Ca2+增加。哺乳动物卵子是一个例外，在受精时观察到一系列具有独特特征的Ca2+振荡。在这种背景下，我们讨论关于精子如何触发卵子中Ca2+释放的三种不同理论。我们提出这样一种情况，即精子在配子膜融合后通过将一种特定蛋白质引入卵子细胞质来介导其Ca2+动员效应。我们的论点基于这样一个事实，即只有哺乳动物精子蛋白因子能够触发一种与哺乳动物卵子中精子诱导的Ca2+振荡模式相似的模式。精子因子活性与一种我们称为振荡素的新型信号蛋白相关，该蛋白可能通过一种新机制介导Ca2+释放。
