Monday, December 11, 2006

Molecular and functional characterization of a low-voltage-gated sodium channel from Drosophila melanogaster

Rachel O'Donnell Olson,, Yoshiko Nomura, and Ke Dong. Michigan State University, Entomology, 106 C.I.P.S, East Lansing, MI

Insects appear to have only a single voltage-gated sodium channel gene (e.g., para in Drosophila melanogaster), in contrast to mammalian species, which express up to nine sodium channel genes. Yet, like mammals, insects express diverse sodium currents with different gating properties in vivo, presumably to fulfill distinct functions in different cell types and tissues. The molecular mechanisms by which a single gene generates different sodium currents are not well understood. In a previous study we identified a low-voltage Para sodium channel variant from Drosophila melanogaster. Site-directed mutagenesis and functional characterization of this variant revealed one amino acid residue that is critical for the activation of this sodium channel at low voltages. Interestingly, molecular analysis showed that this amino acid residue is the result of RNA editing. These results illustrate that RNA editing is responsible for generating a low-voltage-activated sodium channel in Drosophila.

Species 1: Diptera Drosophilidae Drosophila melanogaster