Internal GTP stimulates the speract receptor mediated voltage changes in sea urchin spermatozoa membrane vesicles.
Internal GTP stimulates the speract receptor mediated voltage changes in sea urchin spermatozoa membrane vesicles.
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内部 GTP 刺激海胆精子膜囊泡中 speract 受体介导的电压变化。
DOI：
10.1016/0012-1606(88)90242-4
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发表时间：
1988
影响因子：
2.7
通讯作者：
Lee,HC
中科院分区：
文献类型：
--
作者：
Lee,HC
鞭毛膜上电压敏感的Na+/H+交换器负责调节海胆精子的细胞内pH。先前的研究表明，卵磷脂可以通过其对膜电位的超极化作用来调节这种Na+/H+交换剂。本研究探讨了GTP在精子受体介导的这一过程中的作用。用渗透裂解法制备了具有向外K+梯度的鞭毛质膜囊泡。通过阳离子探针diS-C3-(5)和阴离子探针diS-BA-C2-(3)监测囊泡膜电位。结果表明，体内GTP的存在极大地刺激了精子诱导的膜超极化。类似物gtp - γ - s不仅具有活性，而且本身可以诱导部分超极化，并通过添加speract进一步增强。内部GDP部分支持speract效应，而GDPβS、cGMP、GMP和ATP均不支持speract效应。通过增加各种阳离子的外浓度，考察了离子选择性的影响。K+和Rb+消除了超极化，而Cs+没有影响。这些结果表明，内部GTP参与了精子受体和膜超极化之间的耦合，这很可能是由于K+选择通道的激活。
A voltage-sensitive Na+/H+exchanger in the flagellar membrane is responsible for regulating the intracellular pH of the sea urchin spermatozoa. A previous study has shown that the egg peptide speract can modulate this Na+/H+exchanger through its hyperpolarizing effect on the membrane potential. The effect of GTP on this speract receptor mediated process is investigated in this study. Plasma membrane vesicles with an outwardly directed K+gradient were prepared from the isolated flagella by osmotic lysis. Vesicular membrane potential was monitored by a cationic probe, diS-C3-(5), and an anionic probe, diS-BA-C2-(3). Results show that the presence of internal GTP greatly stimulated the speract induced membrane hyperpolarization in this vesicle system. The analog GTPγS was not only active but could, by itself, induce partial hyperpolarization which was further enhanced by speract addition. Internal GDP was partially active in supporting the speract effect, whereas GDPβS, cGMP, GMP, and ATP were all inactive. The ionic selectivity of the speract effect was investigated by increasing the external concentration of various cations. K+and Rb+abolished the hyperpolarization while Cs+had no effect. These results indicate that internal GTP is involved in the coupling between the speract receptor and the membrane hyperpolarization, which is most likely due to the activation of K+selective channels.