FIGURE 2.

PLM-Ser⁶³ antibody performance in co-immunoprecipitation experiments. A, immunoprecipitation (IP) reactions from untreated and PMA-treated (300 nm, 10 min) ARVMs. In untreated cells, sodium pump α1 subunit co-precipitated poorly with PLM-Ser⁶³. Increasing the quantity of Ser⁶³-phosphorylated PLM by activating PKC increased the quantity of sodium pump α1 subunit co-precipitated. B, immunoprecipitation reactions from FT-293 cells stably expressing PLM-YFP. In the absence of PMA, PLM is largely unphosphorylated in these cells and therefore not immunoprecipitated by Ser⁶³ (S63) and Ser⁶⁸ (S68) antibodies. Following PMA treatment, sodium pump α1 subunit is co-precipitated considerably more efficiently with Ser⁶³-phosphorylated than Ser⁶⁸-phosphorylated PLM.