Abstract
Recent studies have suggested that the tick Ixodes ricinus expresses nAChR subtypes which are activated by acetylcholine. Here, we investigated the potential of the Iricα6 subunit to form a functional receptor when expressed in Xenopus laevis oocytes. Electrophysiological recordings using a two-electrode voltage clamp suggested that the Iricα6 subunit can form a functional homomeric receptor when expressed alone or with chaperone proteins such as RIC-3, UNC-50 and UNC-74. We also found that Iricα6 is a non-selective cation channel. ACh-induced currents were blocked by the nicotinic antagonists methyllicaconitine and dihydro-β-erythroidine. In addition, the nicotinic antagonists α-bungarotoxin and mecamylamine elicited agonist-like responses, with EC(50) values of 3.48 nM and 12.60 nM, respectively. These data indicated that Iricα6 homomeric receptors could have different pharmacological properties compared to homomeric receptors expressed in other species.