The VirB9 protein is found in the vir locus of Agrobacterium Ti plasmids where it is involved in a type IV secretion system . VirB9 is a homolog of the F-type conjugative transfer system TraK protein (which is believed to be an outer membrane pore-forming secretin, TIGR02756) as well as the Ti system TrbG protein. [Cellular processes, Conjugation]
Jiyao W et al.(2023). "The conserved domain database in 2023.",