The Yersinia enterocolitica O:8 periplasmic binding-protein- dependent transport system consisted of four proteins: the periplasmic haemin-binding protein HemT, the haemin permease protein HemU, the ATP-binding hydrophilic protein HemV and the haemin-degrading protein HemS (this family). The structure for HemS has been solved and consists of a tandem repeat of this domain.

1: Transport of haemin across the cytoplasmic membrane through a haemin-specific periplasmic binding-protein-dependent transport system in Yersinia enterocolitica. Stojiljkovic I, Hantke K; Mol Microbiol 1994;13:719-732. PMID:7997183