O'Toole C M, Arnoult C, Darszon A, Steinhardt R A, Florman H M
Department of Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA.
Mol Biol Cell. 2000 May;11(5):1571-84. doi: 10.1091/mbc.11.5.1571.
Fertilization occurs after the completion of the sperm acrosome reaction, a secretory event that is triggered during gamete adhesion. ZP3, an egg zona pellucida glycoprotein, produces a sustained increase of the internal Ca(2+) concentration in mouse sperm, leading to acrosome reactions. Here we show that the sustained Ca(2+) concentration increase is due to the persistent activation of a Ca(2+) influx mechanism during the late stages of ZP3 signal transduction. These cells also possess a Ca(2+) store depletion-activated Ca(2+) entry pathway that is open after treatment with thapsigargin. Thapsigargin and ZP3 activate the same Ca(2+) permeation mechanism, as demonstrated by fluorescence quenching experiments and by channel antagonists. These studies show that ZP3 generates a sustained Ca(2+) influx through a store depletion-operated pathway and that this drives the exocytotic acrosome reaction.
受精发生在精子顶体反应完成之后，顶体反应是一种在配子黏附过程中触发的分泌事件。ZP3是一种卵子透明带糖蛋白，可使小鼠精子内部Ca(2+)浓度持续升高，从而引发顶体反应。我们在此表明，Ca(2+)浓度的持续升高是由于在ZP3信号转导后期Ca(2+)内流机制的持续激活。这些细胞还具有一种Ca(2+)储存耗尽激活的Ca(2+)进入途径，在用毒胡萝卜素处理后该途径会开放。荧光猝灭实验和通道拮抗剂实验表明，毒胡萝卜素和ZP3激活相同的Ca(2+)渗透机制。这些研究表明，ZP3通过一种储存耗尽操作途径产生持续的Ca(2+)内流，并且这驱动了顶体的胞吐反应。
