Gaegurin 4, a peptide antibiotic of frog skin, forms voltage-dependent channels in planar lipid bilayers

H. J. Kim, S. K. Han, J. B. Park, H. J. Baek, B. J. Lee, Pan Dong Ryu

Research output: Contribution to journalArticlepeer-review

21 Scopus citations


Gaegurin 4 (GGN4) is a cationic peptide of 37 amino acids (MW 3748) isolated from the skin of Rana rugosa. It has shown a broad spectrum antimicrobial activity in vitro against Gram-negative and -positive bacteria, fungi and protozoa. To understand its mechanism of antimicrobial action, we examined the effect of GGN4 on the membrane conductance and the electrical properties of GGN4-induced pores in planar lipid bilayers under voltage clamp. Natural and synthetic GGN4 (0.01-1 μg/mL) increased the membrane conductance in a concentration-dependent manner, but GGN4 (1-23), an N- terminal fragment of the peptide with little antimicrobial activity, failed to increase the conductance. At symmetrical 100 mM KCl, unitary conductances of about 120 pS were frequently observed. Their current-voltage relations were linear and open state probabilities were close to 1, but longer closing events were seen more frequently at negative voltages. In addition, GGN4- induced pores were selective for cation over anion, the permeability ratio of K+ to Cl- being 6: 1 in neutral and 7: 1 in acidic lipid bilayers. In conclusion, our results indicate that GGN4 forms voltage-dependent and cation-selective pores in planar lipid bilayers. The ionophoric property of GGN4 is likely to contribute to its antimicrobial activity.

Original languageEnglish (US)
Pages (from-to)1-7
Number of pages7
JournalJournal of Peptide Research
Issue number1
StatePublished - 1999
Externally publishedYes


  • Cation selective channel
  • Gaegurin 4
  • Membrane conductance
  • Peptide antibiotic
  • Planar lipid bilayer
  • Voltage dependence

ASJC Scopus subject areas

  • Biochemistry
  • Endocrinology


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