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Blepharismins, produced by the protozoan, Blepharisma japonicum , form ion‐permeable channels in planar lipid bilayer membranes
Author(s) -
Muto Yoshinori,
Matsuoka Tatsuomi,
Kida Akemi,
Okano Yukio,
Kirino Yutaka
Publication year - 2001
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(01)03110-6
Subject(s) - biophysics , bilayer , membrane , ion channel , lipid bilayer , chemistry , phospholipid , conductance , biology , biochemistry , receptor , mathematics , combinatorics
Blepharismins are polycyclic quinones found in the pigment granules of the ciliated protozoan, Blepharisma . Exposure to purified blepharismins results in lethal damage to several other ciliates. We here report that, at cytotoxic concentrations, blepharismins formed cation‐selective channels in planar phospholipid bilayer membranes. The channels formed in a diphytanoylphosphatidylcholine bilayer had a K + /Cl − permeability ratio of 6.6:1. Single channel recordings revealed the conductance to be quite heterogeneous, ranging from 0.2 to 2.8 nS in solutions containing 0.1 M KCl, possibly reflecting different states of aggregation of blepharismin. Our observations suggest that channel formation is a cytotoxic mechanism of blepharismin's action against predatory protozoa.