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Biochem Biophys Res Commun. 2007 Mar 23;354(4):1052-7. Epub 2007 Jan 24.

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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1
Tropical Technology Center Ltd, 5-1 Suzaki, Uruma, Okinawa, Japan. tikehara@ttc.co.jp

Abstract

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 His(8)-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.

PMID:
17274953
DOI:
10.1016/j.bbrc.2007.01.085
[Indexed for MEDLINE]
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