This domain is found as 1 to 5 copies in lipoproteins that are involved in superinfection exclusion. Proteins in this group have been shown to act at the stage of DNA release from the phage head into the cell [1]. This domain shows a three-helix bundle belonging to the HTH superfamily [2].

1: Comparison of the lysogeny modules from the temperate Streptococcus thermophilus bacteriophages TP-J34 and Sfi21: implications for the modular theory of phage evolution. Neve H, Zenz KI, Desiere F, Koch A, Heller KJ, Brussow H; Virology. 1998;241:61-72. PMID:9454717

2: X-ray structure of a superinfection exclusion lipoprotein from phage TP-J34 and identification of the tape measure protein as its target. Bebeacua C, Lorenzo Fajardo JC, Blangy S, Spinelli S, Bollmann S, Neve H, Cambillau C, Heller KJ; Mol Microbiol. 2013;89:152-165. PMID:23692331