Methylation of the C-terminal leucine residue of the PP2A catalytic subunit is unnecessary for the catalytic activity and the binding of regulatory subunit (PR55/B)

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• 作者：Tsuyoshi Ikehara ; Satsuki Ikehara ; Shihoko Imamura ; Fukiko Shinjo ; Takeshi Yasumoto
• 关键词：Protein phosphatase 2A ; Catalytic subunit ; Carboxyl-methylation ; PME-1 ; Holoenzyme assembly ; Phosphatase activity
• 刊名：Biochemical and Biophysical Research Communications
• 出版年：2007
• 出版时间：23 March 2007
• 年：2007
• 卷：354
• 期：4
• 页码：1052-1057
• 全文大小：447 K

文摘

Protein phosphatase 2A (PP2A) is composed of structural (A), catalytic (C), and regulatory (B) subunits. The catalytic subunit (PP2A_C) undergoes reversible carboxyl-methylation and -demethylation at its C-terminal leucine residue (Leu309), catalyzed by PP2A-methyltransferase (PMT) and PP2A methylesterase (PME-1), respectively. In this study, we observed that the activity of PP2A was largely unaffected by the addition of PME-1, and that the regulatory subunit (PR55/B) could bind demethylated PP2A_D. Furthermore, to study the precise effect of Leu309 demethylation on PP2A activity, we generated two His₈-tagged mutant versions of PP2A_C containing an alanine residue in place of Leu309, and a deletion of Leu309. Both recombinant mutants exhibited phosphatase activity. In addition, we demonstrated that both mutants could constitute a holoenzyme with the regulatory A and B subunits. Our collective results indicate that methylation of Leu309 of PP2A_C is unnecessary for the PP2A activity and the binding of PR55/B.