Relating ligand binding and activation gating in nicotinic acetylcholine receptors
Nicotinic acetylcholine receptors (nAChRs) belong to the superfamily of cys-loop neurotransmitter-gated ion channels. They are expressed in different neuronal and non-neuronal cell types throughout the body, where they mediate fast synaptic cholinergic transmission. nAChR current responses are characterized by a rapid activation upon acetylcholine binding followed by a complex desensitization in the presence of the agonist. While the activation behavior is well understood, the desensitization is still a matter of debate. This project is intended to contribute to the understanding of the desensitization process in adult muscle-type nAChRs.
Because desensitized states are high-affinity states, which are electrically silent, the technical focus will be on the confocal patch-clamp fluorometry (cPCF), an approach combining electrophysiological patch-clamp techniques with confocal fluorescence microscopy. Using a fluorescently tagged acetylcholine analogue, this approach allows not only to control and to monitor receptor activation but also to simultaneously read out ligand binding. In contrast to pure electrophysiological approaches, state-dependent ligand binding can be monitored directly, thus contributing to a more complete picture of the desensitization process.
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