This entry describes a group of DNA-binding response regulator proteins that associate with histidine kinase (<db_xref db="TIGRFAMS" dbkey="TIGR03785"/>) to form a two-component system. This system co-occurs with a proteobacterial variant form of the protein sorting transpeptidase called sortase (<db_xref db="TIGRFAMS" dbkey="TIGR03784"/>), and a single target protein for the sortase. Sortase system response regulator