Figure 5.

The proteosomal inhibitor lactacystin does not affect agonist-promoted down-regulation internalization of the M₂ mAChR in MEFwt. MEFwt cells were transfected with HA-M₂ mAChR and, after 24 hr cells were incubated for 20 min with or without 10 μM lactacystin then treated with 1 mM carbachol for 30 min. Lactacystin has no effect on the internalization of the M₂ mAChR receptor in response to agonist. Internalization was determined using [³H]-NMS binding in whole cells as described in methods. Data are [³H]-NMS bound per well (plated at 1 × 10⁵ cells) and are presented as mean ± standard deviation from three independent experiments with duplicate data points. Statistical analysis was performed using a paired t-test, * indicates p ≤ 0.05; (compared to paired untreated control), ns indicates not significant.