Identification of DNA-protein complexes using an improved, combined western blotting-electrophoretic mobility shift assay (WEMSA) with a fluorescence imaging system.

Electrophoretic Mobility Shift Assays (EMSAs) are used to detect DNA-protein interactions. With this type of assay it is difficult to distinguish between specific and non-specific DNA-protein complexes or to define which protein binds to the DNA. Here we describe a novel Western blot-combined EMSA (WEMSA) variant for a fluorescence imaging system which permits easy identification of specific DNA-protein-complexes. This method also allows investigation of several DNA-protein complexes in parallel. We have identified and distinguished clearly between the SP1- and EGR1-DNA-protein complexes which exhibit overlapping binding to the GC-BOX of the mPGES-1 promoter.