Characterisation of insect nicotinic acetylcholine receptors by heterologous expression

As with other neurotransmitter receptors and ion channels, characterisation ofnicotinic acetylcholine receptors (nAChRs) has relied heavily on studies conducted with cloned receptors expressed in artificial expression systems. Although much has been achieved in recent years by such studies, considerable problems have been encountered in the heterologous expression of several nAChR subtypes; problems that have been particularly pronounced for insect nAChRs. Here we will review studies that have been conducted with nAChRs cloned from insects, with emphasis on experimental strategies that have been employed in an attempt to circumvent the problems associated with inefficient heterologous expression of insect nAChRs. These approaches include the expression of hybrid nAChRs (containing insect nAChR subunit co-expressed with vertebrate subunits), artificial subunit chimeras and the co-expression of molecular chaperones such as RIC-3.