GONADOTROPIN STIMULATES OOCYTE TRANSLATION BY INCREASING MAGNESIUM ACTIVITY THROUGH INTRACELLULAR POTASSIUM MAGNESIUM EXCHANGE
GONADOTROPIN STIMULATES OOCYTE TRANSLATION BY INCREASING MAGNESIUM ACTIVITY THROUGH INTRACELLULAR POTASSIUM MAGNESIUM EXCHANGE
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DOI：
10.1073/pnas.86.24.9652
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发表时间：
1989-12-01
影响因子：
11.1
通讯作者：
TLUCZEK, LJM
中科院分区：
文献类型：
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作者：
HOROWITZ, SB;TLUCZEK, LJM
我们以前表明，促性腺激素增加爪蟾卵母细胞中的K+活性，这是一个增加翻译的信号。然而，K+不需要直接控制合成，但可能通过一个未识别的下游效应子起作用。使用显微注射改变卵母细胞的盐含量，并伴随测量[3H]亮氨酸掺入，我们发现，在Mg 2+的微小变化大大影响翻译率。(Ca2影响不大）。通过测量细胞内离子活性，我们发现卵母细胞阳离子存在于缓冲液样（离子交换）平衡，其中K+和Mg 2+是优势的单价和二价阳离子。因此，增加细胞K+活性可能会通过引起Mg 2+活性上升来增加翻译。如果是这样的话，激素处理或K+注射产生的翻译速率增加将被EDTA（一种Mg2+螯合剂）阻止。这一预测得到了验证和证实。我们的结论是，当促性腺激素增加K+活性时，细胞的内部离子交换平衡被改变，从而增加Mg2+活性，这上调翻译。
We previously showed that gonadotropin increases the K+ activity in Xenopus oocytes and that this is a signal for increased translation. However, K+ need not act to control synthesis directly but may act through an unidentified downstream effector. Using microinjection to vary the salt content of oocytes and concomitantly measuring [3H]leucine incorporation, we found that small changes in Mg2+ greatly affected translation rates. (Ca2+ had little influence). By measuring intracellular ion activities, we found that oocyte cations existed in a buffer-like (ion-exchange) equilibrium in which K+ and Mg2+ are the preponderant monovalent and divalent cations. Hence, increasing cellular K+ activity might increase translation by causing Mg2+ activity to rise. If so, the increased translation rates produced by hormone treatment or K+ injection would be prevented by EDTA, a Mg2+ chelating agent. This prediction was tested and confirmed. We conclude that, when gonadotropin increases K+ activity, the cell''s internal ion-exchange equilibrium is altered thereby increasing Mg2+ activity and this up-regulates translation.