Sequence features of Rid family members. (A) Typical trimeric organization of a RidA protein, Escherichia coli TdcF. (B) TdcF active site with bound serine molecule. Residues of adjacent monomers are colored red or blue. (C) Sequence logos show the conservation and relative frequencies of residues in the archetypal RidA and seven subfamilies (Rid1-Rid7). The six regions shown correspond to the footprint regions used to differentiate the subfamilies.