Figure 7. Agonist binding to M1S2-FlAsH and wild-type m1 receptor reconstituted in phospholipid vesicles.

Cch binding to wild-type m1 receptor (A) and in vitro labeled M1S2-FlAsH (B) after their reconstitution into phospholipid vesicles was measured by competition with 2 nM [³H]QNB. Receptors were reconstituted into phospholipid vesicles with (circles) or without (triangle) Gα_qβ1γ2. When indicated, 50 µM GTPγS was added in the binding reaction (open circle). Data are averages of duplicate measurements and are expressed as percent of maximum bound [³H]QNB. Error bars indicate the range. Binding in the presence of Gα_q (no GTPγS ) was fitted with a two-site binding equation. Binding in the absence of Gα_q (filled triangle) or in the presence of added GTPγS (open circle) was fitted with a one-site binding equation.