Probably part of the ABC transporter complex MntABCD involved in manganese import. Probably responsible for the translocation of the substrate across the membrane. The complex is probably composed of two ATP-binding proteins (MntB), two transmembrane proteins (MntC and MntD) and a solute-binding protein (MntA). Repressed by MntR in the presence of manganese. Belongs to the ABC-3 integral membrane protein family.