Differential release of guinea pig sperm acrosomal components during exocytosis
Differential release of guinea pig sperm acrosomal components during exocytosis
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DOI：
10.1095/biolreprod64.1.148
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发表时间：
2001-01-01
影响因子：
3.6
通讯作者：
Gerton, GL
中科院分区：
文献类型：
--
作者：
Kim, KS;Foster, JA;Gerton, GL
精子顶体的内容物在生化和形态学水平上是有区室的。在生物化学上，顶体可被认为由两个区室组成：一个区室由易溶蛋白质组成，另一个区室含有颗粒状顶体基质。为了检验这一假设，即区室化会影响豚鼠精子分泌过程中顶体组分的释放，我们研究了特定蛋白质的存在和顶体状态之间的关系，并监测了顶体组分在诱导精子周围介质中的恢复，以进行胞吐与离子载体A23187。富含半胱氨酸的分泌蛋白2（CRISP-2），顶体的可溶性成分，迅速失去后不久，离子载体处理的顶体。然而，顶体基质成分仍然与精子的时间较长。AM 67是一种基质成分，也是小鼠精子透明质酸结合蛋白sp 56的豚鼠直向同源物，其释放速率比CRISP-2慢，但比其他两种基质蛋白AM 50和顶体蛋白原的释放速率快。与它们从精子中释放的同时，AM 50和顶体酶原被posteraditionally修饰，可能是通过蛋白水解。顶体酶原从基质中的释放似乎与这种蛋白质转化为具有酶活性的顶体酶蛋白酶有关。这些结果提供了强有力的支持的假设，即区室化在调节顶体胞吐过程中的蛋白质的释放中起着重要的作用。顶体基质蛋白在诱导顶体胞吐作用后仍与精子长时间结合，表明过渡性顶体中间体在受精过程中可能具有重要功能。
The contents of the sperm acrosome are compartmentalized at the biochemical and morphological levels. Biochemically, the acrosome can be considered to be comprised of two compartments: one consisting of readily soluble proteins and one containing a particulate acrosomal matrix. To test the hypothesis that compartmentalization affects the release of acrosomal components during the course of secretion in guinea pig sperm, we examined the relationship between the presence of specific proteins and acrosomal status and monitored the recovery of acrosomal constituents in the medium surrounding sperm induced to undergo exocytosis with the ionophore A23187. Cysteine-rich secretory protein 2 (CRISP-2), a soluble component of the acrosome, was rapidly lost from the acrosome soon after ionophore treatment. However, acrosomal matrix components remained associated with the sperm for longer periods. AM67, a matrix component and the guinea pig orthologue of the mouse sperm zona pellucida-binding protein sp56, was released at a slower rate than was CRISP-2 but at a faster rate than were two other matrix proteins, AM50 and proacrosin. Coincident with their release from the sperm, AM50 and proacrosin were posttranslationally modified, probably by proteolysis. The release of proacrosin from the matrix appears associated with the conversion of this protein to the enzymatically active acrosin protease. These results provide strong support for the hypothesis that compartmentalization plays a significant role in regulating the release of proteins during the course of acrosomal exocytosis. Acrosomal matrix proteins remain associated with the sperm for prolonged periods of time following the induction of acrosomal exocytosis, suggesting that transitional acrosomal intermediates may have significant functions in the fertilization process.