Underlie a Current with Properties Similar to the Native Current in the Moth Spodoptera littoralis Olfactory Receptor Neurons

Responses of insect olfactory receptor neurons (ORNs) involve an entry of Ca 2+ through olfactory heterodimeric receptor complexes. In moths, the termination of ORN responses was found to strongly depend on the external Ca 2+ concentration through the activation of unknown Ca 2+ -dependent Cl 2 channels. We thus investigated the molecular identity of these Cl 2 channels. There is compelling evidence that bestrophins form Cl 2 channels when expressed in heterologous systems. Here we provide evidence that antennae of the moth Spodoptera littoralis express three transcripts encoding proteins with hallmarks of bestrophins. One of these transcripts, SlitBest1b, is expressed in ORNs. The heterologous expression of SlitBest1b protein in CHO-K1 cells yielded a Ca 2+ -activated Cl 2 current that shares electrophysiological properties with the native Ca 2+ -activated Cl 2 current of ORNs. Both currents are anionic, present similar dependence on the intracellular Ca 2+