Part of an ABC transporter complex involved in the uptake of all common nucleosides (PubMed:20595258). Responsible for energy coupling to the transport system (Probable). The complex is composed of two ATP-binding proteins (NupA), two transmembrane proteins (NupB and NupC) and a solute-binding protein (BmpA). Constitutively expressed. Mutant is unable to grow on inosine as a sole purine source. Mutant shows slower uptake of uridine. The double mutant uriP-nupA is impaired in uridine transport. Belongs to the ABC transporter superfamily.