p-PKR dimer phosphorylates PPP2R5A

PPP2R5A, as a subunit of the phosphatase PP2A complex, can regulate the cellular location, substrate specification, and protein phosphatase function of PP2A. Protein kinase R (PKR, EIF2AK2) phosphorylates PPP2R5A at S28, which results in mitochondrial localization of PPP2R5A and activation of the PP2A holoenzyme. In contrast, silencing PKR significantly suppressed the activity of PP2A. PP2A activation supports apoptotic processes that likely include inactivation of BCL2 by dephosphorylation (Xu & Williams, 2000; Ruvolo et al, 2008; Yang et al, 2010; reviewed by Mao et al, 2018).

PPP2R5A 作为磷酸酶 PP2A 复合体的亚基，能够调节 PP2A 的细胞定位、底物特异性和蛋白磷酸酶功能。蛋白激酶 R（PKR，EIF2AK2）在 S28 位点磷酸化 PPP2R5A，导致其定位于线粒体并激活 PP2A 全酶。相反，沉默 PKR 显著抑制了 PP2A 的活性。PP2A 的激活支持凋亡过程，此过程可能包括通过去磷酸化使 BCL2 失活（Xu & Williams，2000；Ruvolo 等人，2008；Yang 等人，2010；Mao 等人综述，2018）。