Competitive Assay

WS via (by novalidaddress from
Tue Apr 26 15:03:42 EST 2011

Hi Juan,

if you want to have competition, you have to mix your ligands *before*
you add them to your cells. If you add one of them first, it binds
well to the receptor (a few socend are enough) and it will take
indefinite time until an equilibrium is reached when you add the
competitor. But you may use this setup for measuring turnover. Then
it's called a pulse - chase experiment.

Remember to add more (ligand + competitor) than you have receptors.
You want competition, not complete binding.

PS for a new topic, please start a new thread!

Have fun!


On Apr 26, 3:53 pm, "Juan Li" <j... from> wrote:
> Hello everyone,
> I would like to run a competitive assay between unlabeled ligand and
> FITC-labeled ligand. How should the 2 compounds be incubated, together in a
> single incubation step or one after another? What's the advantage or
> disadvantage of them?
> Any suggestions?
> Thanks!
> Juan

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