Method for detecting intracellular interaction between biomolecules

Method of detecting interactions between biomolecules or a translocation or conformational change of biomolecules in living cells, comprising the following steps:

• 1) labeling a first biomolecule, in a living cell, with a first fluorescent compound having a long fluorescence lifetime;
• 2) labeling at least one second biomolecule, in said living cell, with a second fluorescent compound;
• 3) subjecting the living cells to a specific stimulation adapted to the biological response to be studied, in the presence or absence of a compound belonging to a bank of test molecules;
• 4) subjecting the living cells to a light source whose wavelength excites said first long-lived fluorescent compound;
• 5) measuring the intensity of the fluorescence emitted by said first and second fluorescent compounds, and calculating the ratio between the fluorescence intensities of said first fluorescent compound and said second fluorescent compound, or measuring the lifetime of the first or second fluorescent compound;
• and
• 6) comparing the measured signals with those obtained before stimulation of the cells, said first and at least second fluorescent compounds being TR-FRET partners.