Purification and properties of a transcriptional activator. The cII protein of phage lambda.

We have purified the phage lambda transcriptional activator protein cII. The procedure described allows cII to be obtained in both high purity and yield, and thus allows detailed physical and chemical analysis. We demonstrate that cII in solution is a tetrameric protein and that it undergoes specific processing at its NH2-terminal end. In addition, the protein is characterized as to its molar extinction coefficient, molecular weight, amino acid composition, isoelectric point, alpha-helical content, and antigenic capability.