The biochemistry of the acrosome reaction
The biochemistry of the acrosome reaction
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DOI：
10.1093/molehr/3.3.195
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发表时间：
1997-03-01
影响因子：
4
通讯作者：
Spungin, B
中科院分区：
文献类型：
--
作者：
Breitbart, H;Spungin, B
精子与卵母细胞透明带 (ZP) 的结合是通过位于精子前头部区域的特定受体发生的。透明带结合刺激精子进行顶体反应，导致水解酶的释放和新膜结构域的暴露，这两者对于受精都是必需的。我们认为 ZP 与质膜中至少两种不同的受体结合。 One (R) 是一种 G(i) 偶联受体，可激活磷脂酶 C (PLC)beta(1)。另一个 (TK) 是与 PLC gamma 偶联的酪氨酸激酶受体。与 R 结合将调节腺苷酸环化酶 (AC)，导致 cAMP 和蛋白激酶 (PKA) 激活升高。 PKA 激活顶体外膜中的电压依赖性 Ca2+ 通道，将 Ca2+ 从顶体内部释放到胞质溶胶。这是 [Ca2+](i) (I) 的第一次相对较小的上升，导致 PLC 伽马激活。 PLC二酰甘油(DAG)和肌醇三磷酸(IP3)水解磷脂酰肌醇二磷酸(PIP2)的产物会导致PKC转位至质膜并被激活。 PKC 在质膜中打开电压依赖性 Ca2+ 通道 (L)，导致 [Ca2+](i) 出现第二个 (II) 更高的增加。 G(i) 或 TK 还可以激活 Na+/H+ 交换剂，导致胞质溶胶碱化。 PKC 还激活磷脂酶 A(2) (PLA(2))，从膜磷脂生成花生四烯酸 (AA)。 AA 会分别通过环氧合酶 (COX) 和脂氧合酶 (LOX) 转化为前列腺素 (PG) 和白细胞三烯 (LT)。 [Ca2+](i) 和 pH 值的增加导致膜融合和顶体胞吐作用。
The binding of the spermatozoon to the oocyte zona pellucida (ZP) occurs via specific receptors localized over the anterior head region of the spermatozoon. Zona pellucida binding stimulates the spermatozoa to undergo the acrosome reaction resulting in the release of hydrolytic enzymes and in the exposure of new membrane domains, both of which are essential for fertilization. We suggest that ZP binds to at least two different receptors in the plasma membrane. One (R) is a G(i)-coupled receptor that activates phospholipase C (PLC)beta(1). The other (TK) is a tyrosine kinase receptor coupled to PLC gamma. Binding to R would regulate adenylyl cyclase (AC) leading to elevation of cAMP and protein kinase (PKA) activation. The PKA activates a voltage-dependent Ca2+ channel in the outer acrosomal membrane which releases Ca2+ from the interior of the acrosome to the cytosol. This is the first, relatively small, rise in [Ca2+](i) (I) which leads to activation of the PLC gamma. The products of phosphatidyl-inositol bisphosphate (PIP2) hydrolysis by PLC diacylglycerol (DAG) and inositol-trisphosphate (IP3) will lead to PKC translocation to the plasma membrane and its activation. PKC opens a voltage-dependent Ca2+ channel (L) in the plasma membrane, leading to the second (II) higher increase in [Ca2+](i). The G(i) or TK can also activate an Na+/H+ exchanger leading to alkalization of the cytosol. PKC also activates phospholipase A(2) (PLA(2)) to generate arachidonic acid (AA) from membrane phospholipids. AA will be converted to prostaglandins (PG) and leukotriens (LT) by the enzymes cyclooxygenase (COX) and lipoxygenase (LOX) respectively. The increase in [Ca2+](i) and pH leads to membrane fusion and acrosomal exocytosis.