Members of this protein family have two copies of the ABC transporter ATP-binding cassette, but are found outside the common ABC transporter operon structure that features integral membrane permease proteins and substrate-binding proteins encoded next to the ATP-binding cassette (ABC domain) protein. The member protein ChvD from Agrobacterium tumefaciens was identified as both a candidate to interact with VirB8, based on yeast two-hybrid analysis, and as an apparent regulator of VirG. The general function of this protein family is unknown.
Jiyao W et al.(2023). "The conserved domain database in 2023.",