title: Characterization of a novel radiolabeled peptide selective for a subpopulation of voltage-gated potassium channels in mammalian brain.
abstract: BgK, a 37-amino acid voltage-gated potassium (Kv) 1 channel blocker isolated from the sea anemone Bunodosoma granulifera, can be modified at certain positions to alter its pharmacological profile (Alessandri-Haber, N., Lecoq, A., Gasparini, S., Grangier-Macmath, G., Jacquet, G., Harvey, A. L., de Medeiros, C., Rowan, E. G., Gola, M., Ménez, A., and Crest, M. (1999) J. Biol. Chem. 274, 35653-35661). In the present study, we report the design of two BgK analogs that have been radiolabeled with (125)INa. Whereas BgK(W5Y/Y26F) and its radiolabeled derivative, (125)I-BgK(W5Y/Y26F), bind to Kv1.1, Kv1.2, and Kv1.6 channels with potencies similar to those for the parent peptide, BgK, BgK(W5Y/F6A/Y26F) and its monoiodo-tyrosine derivative, (125)I-BgK(W5Y/F6A/Y26F), display a distinctive and unique pharmacological profile; they bind with high affinity to homomultimeric Kv1.1 and Kv1.6 channels, but not to Kv1.2 channels. Interaction of BgK(W5Y/F6A/Y26F) with potassium channels depends on the nature of a residue in the mouth of the channel, at a position that determines channel sensitivity to external tetraethylammonium. In native brain tissue, (125)I-BgK(W5Y/F6A/Y26F) binds to a population of Kv1 channels that appear to consist of at least two sensitive (Kv1.1 and/or Kv1.6) subunits, in adjacent position. Given its unique pharmacological properties, (125)I-BgK(W5Y/F6A/Y26F) represents a new tool for studying subpopulations of Kv1 channels in native tissues.
authors.affiliation: Département d'Ingénierie et d'Etudes des Protéines, Commissariat à l'Energie Atomique Saclay, 91191 Gif sur Yvette cedex, France.
authors.forename: Judith
authors.initials: J
authors.lastname: Racapé
authors.forename: Alain
authors.initials: A
authors.lastname: Lecoq
authors.forename: Régine
authors.initials: R
authors.lastname: Romi-Lebrun
authors.forename: Jessica
authors.initials: J
authors.lastname: Liu
authors.forename: Martin
authors.initials: M
authors.lastname: Kohler
authors.forename: Maria L
authors.initials: ML
authors.lastname: Garcia
authors.forename: André
authors.initials: A
authors.lastname: Ménez
authors.forename: Sylvaine
authors.initials: S
authors.lastname: Gasparini
mesh_terms: D000818:Animals; D001483:Base Sequence; D001921:Brain / Q000378:metabolism*; D002460:Cell Line; D017931:DNA Primers; D006801:Humans; D015640:Ion Channel Gating; D015221:Potassium Channels / Q000378:metabolism*; D051381:Rats
chemical_list: D017931:DNA Primers; D015221:Potassium Channels