french student need help

Patrick F.H. Lai pfhlai at LOOKSMART.COM
Fri Aug 21 17:08:32 EST 1998

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can anyone explain the shift-assay method ?
thanks in advance

(excuse my French)

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Hi !

It's quite simple:
If sth binds your probe, e.g. transcription factor binds a DNA 
fragment that includes the cis-element, then the complex would
migrate slower in a electrophoretic gel.
If the DNA is radio-labelled, bands can be seen in an autoradiogram.
Free probe migrates fast and will be at the bottom.
the complex migrates slower and will be higher up.
thus, it would appear that the formation of the DNA-protein complex
"shifts" the band upwards.
Hence the name "gel shift" assay.
or EMSA for electrophoretic Mobility Shift Assays.
The same thing can be done with RNA fragments.
I don't know if protein:protein interactions can be examined this way.

Pls correct me if I am wrong.

Hope this is useful info.   :-)

Patrick F.H. Lai  < PFHLai at >
Graduate Student
University of Toronto
Toronto, Ontario, Canada

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