This family represents a conserved region within Agrobacterium tumefaciens VirE3. Agrobacterium tumefaciens (a plant pathogen) has a tumour-inducing (Ti) plasmid of which part, the transfer (T)-region, is transferred to plant cells during the infection process. Vir proteins mediate the processing of the T-region and the transfer of a single-stranded (ss) DNA copy of this region, the T-strand, into the recipient cells. VirE3 is a translocated effector protein, but its specific role has not been established [1].

1: Analysis of Vir protein translocation from Agrobacterium tumefaciens using Saccharomyces cerevisiae as a model: evidence for transport of a novel effector protein VirE3. Schrammeijer B, den Dulk-Ras A, Vergunst AC, Jurado Jacome E, Hooykaas PJ; Nucleic Acids Res 2003;31:860-868. PMID:12560481