Förster resonance energy transfer as a probe of membrane protein folding

Guipeun Kang, Ignacio López-Peña, Vanessa Oklejas, Cyril S. Gary, Weihan Cao, Judy E. Kim

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


Abstract The folding reaction of a β-barrel membrane protein, outer membrane protein A (OmpA), is probed with Förster resonance energy transfer (FRET) experiments. Four mutants of OmpA were generated in which the donor fluorophore, tryptophan, and acceptor molecule, a naphthalene derivative, are placed in various locations on the protein to report the evolution of distances across the bilayer and across the protein pore during a folding event. Analysis of the FRET efficiencies reveals three timescales for tertiary structure changes associated with insertion and folding into a synthetic bilayer. A narrow pore forms during the initial stage of insertion, followed by bilayer traversal. Finally, a long-time component is attributed to equilibration and relaxation, and may involve global changes such as pore expansion and strand extension. These results augment the existing models that describe concerted insertion and folding events, and highlight the ability of FRET to provide insight into the complex mechanisms of membrane protein folding. This article is part of a Special Issue entitled: Membrane protein structure and function.

Original languageEnglish (US)
Pages (from-to)154-161
Number of pages8
JournalBiochimica et Biophysica Acta - Biomembranes
Issue number2
StatePublished - Feb 2012
Externally publishedYes


  • Bilayer
  • Fluorescence
  • Keywords
  • OmpA
  • Tryptophan
  • Vesicle

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Cell Biology


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