Na⁺-channel editing and neuronal electrophysiological properties. (a) An electrophoregram showing the sequences of hot spots 3 and 4 (described in b). The left panel shows the hypnos-2P cDNA sequence surrounding these two spots. No editing was seen in the mutant since its cDNA sequence is the same as its genomic sequence; the right panel represents the edited cDNA sequence in wild-type C-S flies. Editing sites are marked by arrowheads. (b) Schematic presentation of the para sodium channel showing hot spots that are edited in its pre-mRNA form. From PCR analyses we found that at least seven hot spots (or nine editing sites) in this Na⁺ channel pre-mRNA are edited by the dADAR. Potentially edited adenosines (labeled A) are shown in bold form, underlined, and numbered in parentheses according to the para Na⁺-channel cDNA sequence (GenBank accession number M32078). (c) Recording of neuronal sodium current using whole-cell voltage clamp. Ca²⁺ and K⁺ currents were blocked using cadmium, 4-AP and TEA (extracellular), and cesium (intracellular; see Methods). This is an example of a Na⁺-channel current from hypnos-2P and C-S. Note that a larger Na⁺ current was seen in hypnos-2P as compared with the wild-type C-S.