Fluorescence gel retardation assay to detect protein-protein interactions.

A gel mobility retardation assay can be used to detect a protein-protein interaction. The assay is based on the electrophoretic mobility of a protein-protein complex being less than that of either protein alone. Electrophoretic mobility is detected by the fluorescence of a green fluorescent protein variant that is fused to one of the protein partners. The assay is demonstrated by using the interaction of the S-protein and S-peptide fragments of ribonuclease A as a case study.