Fluorescence polarization assay to quantify protein-protein interactions: an update

Methods Mol Biol. 2015;1278:323-7. doi: 10.1007/978-1-4939-2425-7_19.


A fluorescence polarization assay can be used to evaluate the strength of a protein-protein interaction. A green fluorescent protein variant is fused to one of the protein partners. The formation of a complex is then deduced from an increase in fluorescence polarization, and the equilibrium dissociation constant of the complex is determined in a homogeneous aqueous environment. The assay is demonstrated by using the interaction of the S-protein and S-peptide fragments of ribonuclease A as a case study.

MeSH terms

  • Fluorescence Polarization / methods*
  • Green Fluorescent Proteins
  • Kinetics
  • Peptide Fragments / chemistry
  • Protein Binding
  • Protein Interaction Mapping / methods*
  • Protein Interaction Maps*
  • Proteins / chemistry*
  • Ribonuclease, Pancreatic / chemistry


  • Peptide Fragments
  • Proteins
  • Green Fluorescent Proteins
  • Ribonuclease, Pancreatic