Effects of anti-G-protein antibodies on competition between agonists and [³H]NMS binding at M₂ receptors after suppression of G_i/o G-proteins expression.

<p>Binding of 1 nM [³H]NMS to membranes from CHO cells expressing M₂ receptors after suppression of expression of G_i/o G-proteins by siRNA was determined in the presence of increasing concentrations (abscissa, log M) of the agonists carbachol (upper left), furmethide (upper right), oxotremorine (lower left), and pilocarpine (lower right). Binding is expressed as per cent of control binding in the absence of agonist. Filled circles, control binding in the absence of antibodies. Open symbols, binding in the presence of anti-G_i/o (circles), anti-G_s/olf (squares) and anti-G_q/11 (diamonds) antibodies. Data are means ± S.E.M of values from 3 experiments performed in quadruplicates. Curves were fitted using equation 3 and results of fits are shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0027732#pone-0027732-t006" target="_blank">Table 6</a>.