This domain family is found in bacteria, and is approximately 60 amino acids in length. The family is found in association with Pfam:PF01555. There are two completely conserved residues (F and S) that may be functionally important. This family is a bacterial phage resistance protein. It functions in a type III restriction/modification enzyme complex. It is part of the methylation subunit of the complex. It binds DNA and methylates it.

1: LlaFI, a type III restriction and modification system in Lactococcus lactis. Su P, Im H, Hsieh H, Kang'A S, Dunn NW; Appl Environ Microbiol. 1999;65:686-693. PMID:9925601