title: Isolation and cDNA cloning of a potassium channel peptide toxin from the sea anemone Anemonia erythraea.
abstract: A potassium channel peptide toxin (AETX K) was isolated from the sea anemone Anemonia erythraea by gel filtration on Sephadex G-50, reverse-phase HPLC on TSKgel ODS-120T and anion-exchange HPLC on Mono Q. AETX K inhibited the binding of (125)I-alpha-dendrotoxin to rat synaptosomal membranes, although much less potently than alpha-dendrotoxin. Based on the determined N-terminal amino acid sequence, the nucleotide sequence of the full-length cDNA (609bp) encoding AETX K was elucidated by a combination of degenerate RT-PCR, 3'RACE and 5'RACE. The precursor protein of AETX K is composed of a signal peptide (22 residues), a propart (27 residues) ended with a pair of basic residues (Lys-Arg) and a mature peptide (34 residues). AETX K is the sixth member of the type 1 potassium channel toxins from sea anemones, showing especially high sequence identities with HmK from Heteractis magnifica and ShK from Stichodactyla helianthus. It has six Cys residues at the same position as the known type 1 toxins. In addition, the dyad comprising Lys and Tyr, which is considered to be essential for the binding of the known type 1 toxins to potassium channels, is also conserved in AETX K.
authors.affiliation: Department of Food Science and Technology, Tokyo University of Marine Science and Technology, Konan-4, Minato-ku, Tokyo 108-8477, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Hasegawa
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Honma
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nagai
authors.forename: Masami
authors.initials: M
authors.lastname: Ishida
authors.forename: Yuji
authors.initials: Y
authors.lastname: Nagashima
authors.forename: Kazuo
authors.initials: K
authors.lastname: Shiomi
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002851:Chromatography, High Pressure Liquid; D003001:Cloning, Molecular; D003063:Cnidaria / Q000737:chemistry / Q000235:genetics*; D018076:DNA, Complementary / Q000235:genetics; D004338:Drug Combinations; D004546:Elapid Venoms / Q000378:metabolism; D007425:Intracellular Membranes / Q000378:metabolism; D008969:Molecular Sequence Data; D010455:Peptides / Q000032:analysis; D026902:Potassium Channel Blockers / Q000494:pharmacology; D024642:Potassium Channels, Voltage-Gated / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification*; D011485:Protein Binding; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D013574:Synaptosomes / Q000378:metabolism
chemical_list: D018076:DNA, Complementary; D004338:Drug Combinations; D004546:Elapid Venoms; D010455:Peptides; D026902:Potassium Channel Blockers; D024642:Potassium Channels, Voltage-Gated; C059983:potassium channel protein I(sk); C020273:dendrotoxin