Probably part of an ABC transporter complex involved in host cell binding either through secretion of an adherence factor or through maintaining the architecture and integrity of the mycobacterial cell envelope (PubMed:17030567). Could be required for host endothelial-cell invasion and/or intracellular survival (PubMed:16586367). The complex is probably composed of two ATP-binding proteins (Rv0986) and two transmembrane proteins (Rv0987). Highly up-regulated during the early stages of invasion of the human blood-brain barrier. Disruption of the gene reduces the ability of M.tuberculosis to bind to host cells. Disruption does not reduce virulence in a mouse model of infection (PubMed:17030567). Invasion of the infant human brain microvascular endothelial-cell monolayer is significantly decreased in transposon mutant (PubMed:16586367). Belongs to the ABC-4 integral membrane protein family.