Figure S1 - Conserved and Distinct Modes of CREB/ATF Transcription Factor Regulation by PP2A/B56γ and Genotoxic Stress

(A) ATF1 is hyperphosphorylated in mouse tissues. Thymus or spleen extracts were treated with vehicle or lambda phosphatase prior to analysis by immunoblotting with α-ATF1 and α-CREB antibodies. (B) ATF1E40D,D43E is detected by α-pCREB108/111/114 antibodies. HEK 293T cells were transfected with wild-type FLAG-ATF1 or FLAG-ATF1E40D,D43E expression plasmids. Overexpressed and endogenous ATF1 proteins were detected with α-ATF1 and α-pCREB108/111/114 antibodies. The detection of FLAG-ATF1E40D,D43E with α-pCREB108/111/114 provides evidence that the conserved ATM/CK cluster is phosphorylated in intact cells.
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(A) 激活转录因子1（ATF1）在小鼠组织中呈高度磷酸化状态。将胸腺或脾脏提取物分别用对照溶剂（vehicle）或λ磷酸酶（lambda phosphatase）处理后，使用α-ATF1抗体与α-cAMP应答元件结合蛋白（CREB）抗体进行免疫印迹（immunoblotting）分析。
(B) ATF1E40D,D43E可被α-pCREB108/111/114抗体识别。将野生型FLAG标签融合的ATF1（FLAG-ATF1）或FLAG-ATF1E40D,D43E表达质粒转染至HEK 293T细胞中，通过α-ATF1抗体与α-pCREB108/111/114抗体分别检测过表达及内源性ATF1蛋白。利用α-pCREB108/111/114抗体对FLAG-ATF1E40D,D43E的检测结果，可证实保守的ATM/CK激酶簇在完整细胞中发生了磷酸化修饰。
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