A predicted immunity protein, with an alpha+beta fold and a conserved C-terminal tryptophan residue. The protein is present in a wide range of bacteria in polymorphic toxin systems as an immediate gene neighbour of the toxin gene [1].

1: Evolution of the deaminase fold and multiple origins of eukaryotic editing and mutagenic nucleic acid deaminases from bacterial toxin systems. Iyer LM, Zhang D, Rogozin IB, Aravind L; Nucleic Acids Res. 2011; [Epub ahead of print] PMID:21890906