EMSA supershift problem - (May/15/2007 )

hello
I have a problem because when I used anti-IgM as control there is alwas a supershift or total modification of the profile of the bands when you compare to nuclear extract alone which is not the case with anti-IgG.(I tried with many probes from other persons of the lab ti test and this was always the same problem) This is a problem because I should use IgM antibodies directed to the proteins of interest and I can't conclude anything .
Have you already use such IgM antibodies on your probe? and was it ok?
thank you in adance

I've never used IgM for supershifts just IgG or polyclonal rabbit sera. I don't know if the different structures of IgG versus IgM makes a difference. Can you titrate down your IgM control ab so you minimise any effect and hopefully you'll see something with your specific IgM ab.

Best wishes,
Ceri