A predicted immunity protein with an alpha+beta fold. Proteins containing this domain are present in bacterial polymorphic toxin systems as an immediate gene neighbour of the toxin gene, usually containing a domain of the Tox-URI1, Tox-URI2 or Tox-ParBL1 families [1]. The gene for this toxin is also found in heterogeneous poly-immunity loci that show variations in structure even between closely related strains.

1: Polymorphic toxin systems: comprehensive characterization of trafficking modes, processing, mechanisms of action, immunity and ecology using comparative genomics. Zhang D, de Souza RF, Anantharaman V, Iyer LM, Aravind L; Biol Direct. 2012;7:18. PMID:22731697