PP2A catalytic subunit pTyr307, R&D Systems, AF3989

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, AF3989 from R&D Systems, does not specifically detect PP2AC pTyr307 over unmodified PP2AC in WB, and the signal is only moderately reduced by phosphatase treatment. Antibody recognition in WB is also sensitive to the methylation state of neighboring Leu309, with increased detection of non-methylated PP2AC. In peptide ELISA, the antibody preferentially detects pTyr307 over unmodified PP2AC; however, the signal is not specific for pTyr307, as crossreactivity is observed with HA-derived phosphotyrosine control peptides