RECA immunological assay as a tool to analyze the SOS response

The content of RECA protein, one of the SOS genes product, was determined in a bacterial extract by a two site-radioimmunometric assay. The variation of the RECA concentration after induction by physical or chemical treatments was used as a probe to analyze the SOS response. Relationships between either the number or the nature of DNA lesions and the level of the relative amplification of RECA have been established. The modulation of the recA gene expression is discussed.