Figure 2.

Role of p85α-SH3 domain in mediating the interaction of PI3K with the Na⁺,K⁺-ATPase α subunits. (a) The presence of Na⁺,K⁺-ATPase α₁ subunits (see Fig. 1b) in the immunoprecipitates with the p85α antibody was examined in OK cells incubated with 1 μM DA for 2.5 min at 23°C in the presence or absence of 10 μM SH3-binding peptide (Calbiochem). Transient cell permeabilization was performed to allow access of the peptide to the cells' interiors. (b) Rubidium transport (nmol of Rb per mg of protein per min) was used as an index of Na⁺,K⁺-ATPase transport activity. Experiments were performed with identical protocols as described in a. Data represent the mean ±SEM of three experiments performed in triplicate. ∗, P < 0.05 (Student's t test).