Fig. 6. Tyrosine dephosphorylation of endogenous Kir2.1 channels at the onset of differentiation. (A) Myoblasts (300x10⁶) were cultured in growth medium (GM) or in differentiation medium for 6 hours (DM 6h). Both populations of myoblasts were treated for 30 minutes preceding lysis with 10 µM bpV(Phen) to avoid unspecific dephosphorylation. An equal amount of proteins (10 mg) from each population was immunoprecipitated with a rabbit anti-Kir2.1 antibody. Immunoprecipitated proteins were separated on SDS-PAGE, and revealed with chicken anti-Kir2.1 antibody (upper lane) and then reblotted with an anti-phosphotyrosine antibody (PT-66, lower lane). Bands were quantified by Optiquant software. (B) The histogram represents the fraction of endogenous Kir2.1 channels that are tyrosine-phosphorylated normalized to the tyrosine-phosphorylated Kir2.1 channels in proliferating conditions. Results were obtained from three independent experiments.