Part of the ABC transporter complex ModABC involved in the transport of molybdenum into the cell (Probable). Binds molybdate and tungstate with high affinity in vitro (PubMed:16879982). The complex is composed of two ATP-binding proteins (ModC), two transmembrane proteins (ModB) and a solute-binding protein (ModA). Belongs to the bacterial solute-binding protein ModA family.