Electrophoretic mobility shift assay analysis of NF-κB DNA binding.

The discovery and characterization of the nuclear factor-kappa B (NF-κB) family of transcription factors was predicated on the technical ability to detect protein binding to defined sequences of DNA. Proteins capable of binding to specific sequences of nucleic acid are detected through the use of the electrophoretic mobility shift assay (EMSA), also called a gel shift assay. While newer techniques, including chromatin immunoprecipitation (ChIP), are widely used to assess NF-κB binding to the promoters and enhancers of specific genes, the EMSA remains a powerful experimental tool to quickly test for the presence of NF-κB that is capable of binding DNA. In this way, the EMSA is a useful general readout of the activation state of the NF-κB pathway and an essential tool for the investigation of this important transcription factor family.