Fusion Reporter Approaches to Monitoring Transmembrane Helix Interactions in Bacterial Membranes

Methods Mol Biol. 2017;1615:199-210. doi: 10.1007/978-1-4939-7033-9_16.


In transenvelope multiprotein machines such as bacterial secretion systems, protein-protein interactions not only occur between soluble domains but might also be mediated by helix-helix contacts in the inner membrane. Here we describe genetic assays commonly used to test interactions between transmembrane α-helices in their native membrane environment. These assays are based on the reconstitution of dimeric regulators allowing the control of expression of reporter genes. We provide detailed protocols for the TOXCAT and GALLEX assays used to monitor homotypic and heterotypic transmembrane helix-helix interactions.

Keywords: GALLEX; Helix–helix interaction; Membrane protein; One-hybrid; Protein-protein interaction; TOXCAT; Transmembrane segment; Two-hybrid; cI repressor.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Membrane / chemistry*
  • Cell Membrane / metabolism
  • Genes, Reporter*
  • Membrane Proteins / chemistry*
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism
  • Protein Binding
  • Protein Interaction Mapping / methods*
  • Protein Structure, Secondary*
  • Recombinant Fusion Proteins / chemistry*
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Two-Hybrid System Techniques*


  • Membrane Proteins
  • Recombinant Fusion Proteins