Identification of sequence-specific DNA-binding proteins by Southwestern blotting

Abstract

We describe a Southwestern blotting method for characterization of both DNA-binding proteins and their specific sites. Proteins are first separated on a sodium dodecyl sulfate (SDS) polyacrylamide gel, then renatured in SDS-free buffer and transferred by electroblotting to an immobilizing membrane, and detected by their ability to bind radiolabeled DNA. The protein(s) interacting with the labeled DNA is visualized by autoradiography. This technique was used in our laboratory to visualize the metal regulatory consensus sequence-binding protein MTF-1 in L cell crude nuclear extracts. © 2009 Humana Press, a part of Springer Science+Business Media, LLC.