Tolstykh T, Lee J, Vafai S, Stock J B
Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA.
EMBO J. 2000 Nov 1;19(21):5682-91. doi: 10.1093/emboj/19.21.5682.
Phosphoprotein phosphatase 2A (PP2A) is a major phosphoserine/threonine protein phosphatase in all eukaryotes. It has been isolated as a heterotrimeric holoenzyme composed of a 65 kDa A subunit, which serves as a scaffold for the association of the 36 kDa catalytic C subunit, and a variety of B subunits that control phosphatase specificity. The C subunit is reversibly methyl esterified by specific methyltransferase and methylesterase enzymes at a completely conserved C-terminal leucine residue. Here we show that methylation plays an essential role in promoting PP2A holoenzyme assembly and that demethylation has an opposing effect. Changes in methylation indirectly regulate PP2A phosphatase activity by controlling the binding of regulatory B subunits to AC dimers.
蛋白磷酸酶2A（PP2A）是所有真核生物中一种主要的磷酸丝氨酸/苏氨酸蛋白磷酸酶。它已被分离为一种异源三聚体全酶，由一个65 kDa的A亚基组成，该亚基作为36 kDa催化C亚基结合的支架，以及多种控制磷酸酶特异性的B亚基。C亚基在一个完全保守的C末端亮氨酸残基处被特定的甲基转移酶和甲酯酶可逆地甲基酯化。在这里，我们表明甲基化在促进PP2A全酶组装中起关键作用，而去甲基化则具有相反的作用。甲基化的变化通过控制调节性B亚基与AC二聚体的结合间接调节PP2A磷酸酶活性。
