Expression of β-arrestin 1 or 2 rescued agonist-promoted internalization of M
mAChRs in MEF KO1/2 cells. Approximately 24 h following co-transfection with constructs encoding M2 mAChRs and β-arrestins, cells were stimulated with 1 mM carbachol for 1 h. A.) Agonist-promoted internalization was determined as described in Methods. Data are presented as the mean ± standard deviation of 5 independent experiments consisting of 8–11 determinants. B.) A representative immunoblot of FLAG-tagged β-arrestin and internal protein control β-actin is shown. Lanes consisted of: non-transfected MEF KO1/2 (1), MEF KO1/2 expressing β-arrestin1 (2), MEF KO1/2 expressing β-arrestin 2 (3), and MEF KO1/2 expressing β-arrestin 1 and 2 (4). Western blot shown is a representative of at least 3 independent experiments.