Runft Linda L, Jaffe Laurinda A, Mehlmann Lisa M
Department of Physiology, University of Connecticut Health Center, Farmington, Connecticut 06030, USA.
Dev Biol. 2002 May 15;245(2):237-54. doi: 10.1006/dbio.2002.0600.
A centrally important factor in initiating egg activation at fertilization is a rise in free Ca(2+) in the egg cytosol. In echinoderm, ascidian, and vertebrate eggs, the Ca(2+) rise occurs as a result of inositol trisphosphate-mediated release of Ca(2+) from the endoplasmic reticulum. The release of Ca(2+) at fertilization in echinoderm and ascidian eggs requires SH2 domain-mediated activation of a Src family kinase (SFK) and phospholipase C (PLC)gamma. Though some evidence indicates that a SFK and PLC may also function at fertilization in vertebrate eggs, SH2 domain-mediated activation of PLC gamma appears not to be required. Much work has focused on identifying factors from sperm that initiate egg activation at fertilization, either as a result of sperm-egg contact or sperm-egg fusion. Current evidence from studies of ascidian and mammalian fertilization favors a fusion-mediated mechanism; this is supported by experiments indicating that injection of sperm extracts into eggs causes Ca(2+) release by the same pathway as fertilization.
受精时启动卵子激活的一个核心重要因素是卵子细胞质中游离钙离子（Ca²⁺）浓度的升高。在棘皮动物、海鞘和脊椎动物的卵子中，Ca²⁺浓度升高是由三磷酸肌醇介导的内质网Ca²⁺释放所致。棘皮动物和海鞘卵子受精时Ca²⁺的释放需要Src家族激酶（SFK）和磷脂酶C（PLC）γ通过SH2结构域介导的激活。虽然一些证据表明SFK和PLC在脊椎动物卵子受精时也可能发挥作用，但似乎不需要SH2结构域介导的PLCγ激活。许多研究致力于确定受精时来自精子的启动卵子激活的因素，这些因素是精子与卵子接触或精子与卵子融合的结果。目前来自海鞘和哺乳动物受精研究的证据支持融合介导机制；这得到了一些实验的支持，这些实验表明将精子提取物注入卵子会通过与受精相同的途径导致Ca²⁺释放。
