Is FRET always performed with CFP-YFP tags? Why is this?

Hi Cynthia,
The answer is not always.
Please look at this link and you will find a good description.
http://probes.invitrogen.com/handbook/boxes/0422.html
Guy

No

all you need is a suitable pair for which the emission spectra of the donor overlaps sufficiently with the excitation spectra of the acceptor to get FRET.

e.g. FITC & TRITC, Cy3 & Cy5, eGFP & Cy3

here's a good teaching guide to get you started

FRET teaching aid

another cool tutorial can be found at

http://www.microscopyu.com/tutorials/java/fluorescence/fpfret/index.html

Thanks Frasermoss for the nice FRET teaching ade module.
Very interesting and informative.
Guy

Thanks for the assistance. This has been very helpful as we initiate FRET experiments. Cynthia