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Updated: Jun 10, 2026

In Vivo Imaging of Transduction Efficiencies of Cardiac Targeting Peptide
Published on: June 11, 2020
A cytotoxic peptide from a marine sponge exhibits ion channel activity through vectorial-insertion into the membrane
Masayuki Iwamoto1, Hirofumi Shimizu, Ikunobu Muramatsu
1Department of Molecular Physiology and Biophysics, University of Fukui Faculty of Medical Sciences, Fukui, Japan.
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.
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