title: Genomic structure of a potassium channel toxin from Heteractis magnifica.
abstract: We provide information on the gene encoding the K+ channel toxin, HmK, of the sea anemone Heteractis magnifica. A series of DNA amplifications by PCR, which included the amplification of the 5'-untranslated region of the gene, showed that an intron of 402 nucleotides separated the sequence that encodes the matured toxin from the signal peptide sequence. A second 264 nucleotide intron interrupted the 5'-untranslated region of the previously reported HmK cDNA. Two possible transcription-initiation sites were identified by primer extension analysis. Corresponding TATA-box consensus sequences, characteristic of a promoter region, were also located from PCR products of uncloned libraries of adaptor-ligated genomic DNA fragments. The coding region for matured HmK is intronless. The same is also true for other sea anemone toxins reported thus far. More notably, a similar intron-exon organization is present in other ion channel-blocking toxins from scorpions implying that molecules having similar functions share a similar organization at the genomic level suggesting a common path of evolution.
authors.affiliation: Department of Biochemistry, National University of Singapore, Singapore.
authors.forename: G S
authors.initials: GS
authors.lastname: Gendeh
authors.forename: M C
authors.initials: MC
authors.lastname: Chung
authors.forename: K
authors.initials: K
authors.lastname: Jeyaseelan
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003064:Cnidarian Venoms / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D016384:Consensus Sequence; D018076:DNA, Complementary; D005091:Exons; D016678:Genome; D007438:Introns; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D026902:Potassium Channel Blockers; D012615:Sea Anemones / Q000235:genetics*; D016385:TATA Box; D014158:Transcription, Genetic
chemical_list: D003064:Cnidarian Venoms; D018076:DNA, Complementary; C108359:HmK toxin, sea anemone; D026902:Potassium Channel Blockers