Figure 4A shows that CadC degradation is coupled to induction of cadA transcription .
These results indicate that the immediate induction of cadA mRNA following stress is correlated with rapid cleavage of CadC .
CadC degradation is coupled to transcriptional induction of cadA .
Therefore , we reasoned that acid stress-induced proteolysis of CadC might be a posttranslational control mechanism for activating membrane-bound CadC because the induction of cadA transcription is accompanied by proteolysis of CadC .