Mechanisms for Increased Levels of Phosphorylation of Elongation Factor-2 during Hibernation in Ground Squirrels

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• 作者：Yun Chen ; Masayuki Matsushita ; Angus C. Nairn ; Zahi Damuni ; Decheng Cai ; Kai U. Frerichs ; and John M. Hallenbeck
• 刊名：Biochemistry
• 出版年：2001
• 出版时间：September 25, 2001
• 年：2001
• 卷：40
• 期：38
• 页码：11565 - 11570
• 全文大小：118K
• 年卷期：v.40,no.38(September 25, 2001)
• ISSN：1520-4995

文摘

Previously, eEF-2 phosphorylation has been identified as a reversible mechanism involved inthe inhibition of the elongation phase of translation. In this study, an increased level of phosphorylationof eukaryotic elongation factor-2 (eEF-2) was observed in the brains and livers of hibernating groundsquirrels. In brain and liver from hibernators, eEF-2 kinase activity was increased relative to that of activeanimals. The activity of protein phosphatase 2A (PP2A), a phosphatase that dephosphorylates eEF-2, wasalso decreased in brain and liver from hibernators. This was associated with an increase in the level ofinhibitor 2 of PP2A (I₂^PP2A), although there was an increase in the level of the catalytic subunit of PP2A(PP2A/C) in hibernating brains and livers. These results indicate that eEF-2 phosphorylation representsa specific and previously uncharacterized mechanism for inhibition of the elongation phase of proteinsynthesis during hibernation. Increased levels of eEF-2 phosphorylation in hibernators appear to be acomponent of the regulated shutdown of cellular functions that permits hibernating animals to toleratesevere reductions in cerebral blood flow and oxygen delivery capacity.