Click on image to view larger version.
Figure 1. Dephosphorylation of Na,K-ATPase 
1-subunit at Ser-18 by PP2A is necessary for its recruitment to the plasma membrane. A) In vitro backphosphorylation assay performed on the immunoprecipitated Na,K-ATPase 1-subunit from 1V5-A549 cells exposed for 5 min to 10 µM dopamine in the presence or absence of 5 nM OA. Upper panel) Shows a representative autoradiography. Lower panel) Depicts a representative Western blot. Graph represents the mean ± SEM of three different experiments. B) ATII cells were exposed for 5 min to 10 µM dopamine in the presence or absence of 5 nM OA, the 1% Triton X-100 soluble fraction was isolated and S18 phosphorylation was studied using the Mck1 Ab (upper panel). Equal loading was demonstrated by stripping the membrane and probing with another Ab against the Na,K-ATPase 1-subunit (lower panel). Graph represents the mean ± SEM of three different experiments. C) ATII cells were exposed for 5 min to 10 µM dopamine in the presence or absence of 5 nM OA, and the amount of Na,K-ATPase abundance at the plasma membrane was studied by biotin-streptavidin pull down and subsequent Western blot. Graph represents the mean ± SEM of three different experiments DA: dopamine; OA: OA; i.b.: immunoblot; i.p.: immunoprecipitation. *P < 0.05, **P < 0.01.
