Purified λ regulatory protein cII positively activates promoters for lysogenic development

Abstract
The bacteriophage .lambda. regulatory protein, cII, was purified and shown to activate positively RNA transcription from the 2 phage promoters which coordinately regulate phage lysogenic development. [Phage .lambda. infects Escherichia coli.] To obtain this protein, the cII gene was cloned into a plasmid vector carrying the strong, regulatable .lambda. phage promoter PL such that it was overproduced to levels approaching 5% of cellular protein.