Imaging protein interactions by FRET microscopy: FRET measurements by sensitized emission

Item Type:	Article
Title:	Imaging protein interactions by FRET microscopy: FRET measurements by sensitized emission
Creators Name:	Verveer, P.J. and Rocks, O. and Harpur, A.G. and Bastiaens, P.I.H.
Abstract:	This protocol describes a method for measuring fluorescence resonance energy transfer (FRET) by the detection of acceptor-sensitized emission. This approach is useful in situations where donor intensities are low and/or there is contamination with high background (auto) fluorescence in the donor channel. However, absorption spectra characteristically exhibit long tails in the higher-energy, shorter-wavelength (blue) region, which may result in the direct excitation of the acceptor molecule in addition to that of the donor, thus resulting in mixing of direct and sensitized emission. Conversely, fluorescence emission tends to tail into the red part of the spectrum, causing donor fluorescence bleed-through into the acceptor detection channel. Corrections for these effects involve the acquisition of fluorescence images of samples containing the donor, the acceptor, and both of these for three different filter settings. The result is an estimation of the sensitized emission, i.e., the emission induced by FRET from the donor to the acceptor alone. Excitation of a donor fluorophore in a FRET pair leads to quenching of the donor fluorescence and increased emission from the acceptor (sensitized emission). This can be normalized using the acceptor emission, measured after specific excitation of the acceptor, to define apparent energy transfer efficiency in each pixel of the image. It is also proportional to the fraction of acceptor molecules that is bound to a donor-tagged molecule. Alternatively, an apparent energy transfer efficiency can also be defined that is proportional to the bound fraction of donor-tagged molecules.
Source:	Cold Spring Harbor Protocols
ISSN:	1559-6095
Publisher:	Cold Spring Harbor Laboratory Press
Volume:	2006
Number:	6
Date:	1 November 2006
Official Publication:	https://doi.org/10.1101/pdb.prot4597
PubMed:	View item in PubMed

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