Protocol to identify ligands of odorant receptors using two-electrode voltage clamp combined with the oocytes heterologous expression system.

Two-electrode voltage clamp (TEVC) combined with the oocytes heterologous expression system is a powerful electrophysiological tool widely used to study the properties of many transmembrane proteins. Here, we describe a protocol using this combined approach to identify the ligands of odorant receptors that form ligand-gated ion channels. We detail the procedures for site-directed mutagenesis, oocyte microinjection, and TEVC recording. This protocol can also be used to identify the key residues and illustrate the structure-function relationships of these proteins. For complete details on the use and execution of this protocol, please refer to Cao et al. (2021).