Modulation of Drosophila sodium channel gating by four TipE-homologous proteins

In mammals, sodium channel alpha-subunits are associated with small beta auxiliary subunits, which modulate the kinetics and voltage-dependence of sodium channel gating. There are no such beta-subunit orthologs in insects. Instead, a TipE protein is considered to be an auxiliary subunit of insect sodium channels. In addition to TipE, there are four TipE-homologous genes (TEH1-4) in the D. melanogaster genome. However, whether these proteins could modulate sodium channel gating remains poorly understood. In this study, we examined the gating properties of Drosophila sodium channel variants co-expressed with or without each of the four TEH proteins in Xenopus oocytes. Our analysis revealed differential modulation of a number of different gating properties by TEH proteins, suggesting distinct roles of individual TEH genes in regulating neuronal excitability.