Molecular cloning of an enhancer binding protein: isolation by screening of an expression library with a recognition...

A novel strategy has been used to isolate a cDNA clone that encodes a DNA binding domain whose recognition properties overlap those of the mammalian transcription factors H2TF1 and NF-kappa B. These two factors are distinguished by their cell type distributions and their relative affinities for related sequence elements in the enhancers of the major histocompatibility complex (MHC) class I and immunoglobulin kappa chain genes. The human cDNA clone was detected by screening a lambda phage expression library with a binding site probe derived from the MHC enhancer. The phage encoded fusion protein binds specifically to both the MHC and kappa gene enhancers. The cDNA hybridizes to a single copy gene that is expressed as a 10 kb mRNA in both B and non-B cells. The strategy used in this study may prove generally useful in the cloning and analysis of sequence-specific DNA binding proteins.