Mobility shift problem...

rebecca rebsilver at
Mon Mar 2 10:31:15 EST 1998

Could the problem be that the binding protein(s) envelope your DNA
fragment, blocking the labelled nucleotides from detection?
Just a theory.

John G. Wise wrote:

> In our gel retardation assay with crude extracts, we see the free DNA
> disappear from the lane with our binding protein, but no shifted band
> appears (we have poly d(I-C) or calf thymus DNA present). When we add
> unlabeled "specific DNA" to the same sample, the free reappears.  Free
> labeled DNA alone gives a nice band. We are using the DIG shift method,
> but have no problem with detection, since free is easily seen and since
> controls with other DNA/binding protein combinations work fine.
> Can anyone help?
> Thanks, John
> email: wise at

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