PP2A catalytic subunit pTyr307, Sigma-Aldrich, SAB4503975

Our team performed a comprehensive review of the scientific literature to identify studies using antibodies against human Protein Phosphatase 2A (PP2A), followed by extraction and evaluation of available data according to the pAbmAbs rating criteria. In this study, Frohner et al. conducted a head-to-head comparison of eight commercially available antibodies against PP2A catalytic subunit phosphorylated at Tyr307 (PP2Ac pTyr307). Antibody performance was evaluated by WB and ELISA, with particular emphasis on specificity for Tyr307 phosphorylation versus other post-translational modifications, including Leu309 methylation. For WB experiments, antibodies were tested using lysates from stably HA-PP2AC-expressing NIH 3T3 cells, transiently transfected HEK293T cells, HAP1 cells, and primary mouse CD4+ T cells under multiple experimental conditions, including phosphatase treatment, modulation of PP2A methylation, kinase activation, and site-directed mutagenesis. Peptide ELISA was performed using synthetic PP2A C-terminal peptides carrying defined combinations of post-translational modifications. Detailed experimental procedures are provided in the original publication (see reference). This antibody, SAB4503975 from Sigma-Aldrich, specifically detects PP2AC pTyr307 over unmodified PP2AC in peptide ELISA. It shows no cross-reactivity with the HA-derived phosphotyrosine control peptides tested and recognition of pTyr307 is only minimally affected by the methylation state of neighboring Leu309. In WB of cell lysates, the antibody detects SrcCA-induced phosphorylation of PP2AC, and the signal is almost completely abolished by phosphatase treatment. However, substantial cross-reactivity with other proteins is observed in SrcCA-overexpressing cells, indicating limited specificity in WB. Antibody recognition in WB is also affected by the methylation state of Leu309 with a preference for non-methylated PP2AC.