I ran a SDS-PAGE, using Kaleidoscope Prestained Standards from BioRad as a molecular weight marker.
I got a nice band for my protein - only visible band. But the problem was - it appeared about 80kDa lower than I expected - the protein is supposed to be 160 kDa, but it showed up as 80kDa, according to the MW marker.
I called the company, they suggested a few possible reasons for that - like degradation of the protein or MW of 160kDa for the protein being in dimers, which as I think, is not the issue.
They sent the positive control (HepG2 cell lysate), and meanwhile i ran another gel, from another kind of tissue, probing for a different, unrelated protein - and it showed up as being 40kDa, instead of 120kDa.
I re-ran the first gel, with the positive control, and the positive control showed the most intensive band around 80kDa, together with the most intensive bands from my samples, so I think there should be something wrong with the MW marker?
What could be a reason for this?
Edited by Margoute, 09 March 2009 - 08:10 AM.