Summary
Energy transfer between two fluorophores reports on molecular distances and interactions.
In depth
Efficiency depends on the 6th power of distance (works at 1 to 10 nm) and spectral overlap. Used for protein interactions, conformational changes and biosensors.
FRET changes can signal binding or conformational shifts. Measurements need controls for bleed-through. FLIM-FRET measures lifetime.
Remember: FRET only occurs when molecules are within about 10 nm.
Forster (fluorescence) resonance energy transfer occurs when an excited donor fluorophore transfers energy without emitting light to a nearby acceptor fluorophore, if their spectra overlap and they lie within about 1 to 10 nm. Efficiency falls with the sixth power of distance, making FRET a sensitive molecular ruler.
In cells, a donor/acceptor pair such as CFP and YFP can be attached to two proteins to see if they interact, or to the ends of one protein to report conformational changes, as in calcium sensors and kinase activity reporters. Measured as increased acceptor emission, or by lifetime (FLIM). Controls for bleed-through are essential.
Example: FRET reveals when a signalling protein changes shape.
Remember: no FRET does not prove no interaction.
Frequently asked questions
What is FRET?
Energy transfer between two fluorophores reports on molecular distances and interactions.
Which area of biology covers FRET, and how advanced is it?
FRET is one of the 51 topics in Lab Methods & Biostatistics. It is rated Advanced, so it suits learners who want specialist depth. Related topics in this area include NMR in Biology, Fluorescent Proteins, Immunofluorescence.
Can you give an example of FRET?
CFP-YFP FRET detects calcium binding to calmodulin.
What should I learn before FRET?
Work through the Beginner topics in Lab Methods & Biostatistics first, such as Scientific Method, Hypothesis, Variables, then return to FRET. Advanced topics assume the Intermediate vocabulary.
What topics are related to FRET?
The closest topics to FRET are NMR in Biology, Fluorescent Proteins, Immunofluorescence, ELISA. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand FRET?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for FRET. To practise the whole of Lab Methods & Biostatistics, use the Lab Methods & Biostatistics quiz.
How is FRET different from NMR in Biology?
FRET: Energy transfer between two fluorophores reports on molecular distances and interactions. NMR in Biology: Nuclear magnetic resonance reveals structures and dynamics of molecules in solution. Read both side by side and note what each one explains.
How should I study FRET step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with NMR in Biology and explain the difference aloud. Finally, take the Lab Methods & Biostatistics quiz and come back to this page for any question you miss.