title: A cytotoxic peptide from a marine sponge exhibits ion channel activity through vectorial-insertion into the membrane.
abstract: A cytotoxic peptide, polytheonamide B (pTB), from marine sponge was examined for cytotoxic spectrum and specific activity to mammalian cells was demonstrated. pTB is composed of alternative D- and L-amino acid residues throughout the 48-mer peptide. This suggests the formation of a β-helix similar to gramicidin channels. Planar bilayer experiments revealed that pTB forms monovalent cation-selective channels, being compatible with the inner pore diameter of ∼4Å for a β-helical structure. pTB penetrated vectorially into the membrane, formed a channel by means of a single molecule, and remained in the membrane. These functional properties may account for specific cytotoxic activity.
authors.affiliation: Department of Molecular Physiology and Biophysics, University of Fukui Faculty of Medical Sciences, Fukui, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Iwamoto
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Shimizu
authors.forename: Ikunobu
authors.initials: I
authors.lastname: Muramatsu
authors.forename: Shigetoshi
authors.initials: S
authors.lastname: Oiki
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D045744:Cell Line, Tumor; D003603:Cytotoxins / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology*; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D008969:Molecular Sequence Data; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology*; D047232:Theonella / Q000737:chemistry*
chemical_list: D003603:Cytotoxins; D047908:Intracellular Signaling Peptides and Proteins; D011506:Proteins; C111717:polytheonamide B