Two sodium-channel genes in Drosophila: implications for channel diversity.
We describe two Drosophila melanogaster transcription units that are highly homologous to a rat Na+-channel cDNA. They appear to encode the major subunits of two distinct Na+-channel proteins. One of these maps to the second chromosome and is identical to a Na+-channel gene whose partial sequence has been previously reported [Salkoff, L., Butler, A., Wei, A., Scavarda, N., Giffen, K., Ifune, K., Goodman, R. & Mandel, G. (1987) Science 237, 744-749]. The other transcription unit maps to position 14C/D, on the X chromosome, close to the paralyzed (para) gene. Mutations in para affect membrane excitability in Drosophila neurons [Ganetzky, B. & Wu, C.F. (1986) Annu. Rev. Genet. 20, 13-44]. Sequence comparisons suggest that two Na+-channel genes arose early in evolution, before the divergence of vertebrate and invertebrate lines.
Ramaswami
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Division of Biology, California Institute of Technology, Pasadena 91125.
Tanouye
M A
MA
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D005075:Biological Evolution; D002874:Chromosome Mapping; D004247:DNA / Q000235:genetics; D015342:DNA Probes; D004331:Drosophila melanogaster / Q000235:genetics*; D014644:Genetic Variation; D008969:Molecular Sequence Data; D009154:Mutation; D009693:Nucleic Acid Hybridization; D051381:Rats; D012689:Sequence Homology, Nucleic Acid; D015222:Sodium Channels / Q000502:physiology*
D015342:DNA Probes; D015222:Sodium Channels; D004247:DNA