This is a viral family of phage zinc-binding transcriptional activators, which also contains cryptic members in some bacterial genomes [1]. The P4 phage delta protein contains two such domains attached covalently, while the P2 phage Ogr proteins possess one domain but function as dimers. All the members of this family have the following consensus sequence: C-X(2)-C-X(3)-A-(X)2-R-X(15)-C-X(4)-C-X(3)-F [2]. This family also includes zinc fingers in recombinase proteins.

1: Escherichia coli K-12 and B contain functional bacteriophage P2 ogr genes. Slettan A, Gebhardt K, Kristiansen E, Birkeland NK, Lindqvist BH; J Bacteriol 1992;174:4094-4100. PMID:1597424

2: The two P2 Ogr-like domains of the delta protein from bacteriophage P4 are required for activity. Julien B, Lefevre P, Calendar R; Virology 1997;230:292-299. PMID:9143285