(A) Co-expressed P2X2/3 and α6β4 receptors; (B) co-expressed P2X2/3 and α6β4β3 receptors. Exemplar inward currents are shown, evoked with 100 μM α,βme-ATP, 100 μM ACh, or a mixture of 100 μM α,βme-ATP+ACh. (C) Co-expressed P2X2 and α6β2 receptors were tested with 100 μM ATP, 10 μM ACh, or a mixture of the two agonists. All graphs summarize experiments from n = 11–13 cells. The ‘predicted’ (Pred.) current for each cell is the arithmetic sum of the Iα,βme-ATP and IACh currents. The ‘Δ’ current for each cell is the predicted current minus the observed Iα,βme-ATP+ACh current. Error bars represent SEM. To provide measureable responses, several subunits were mutated as described in Methods.