Part of the ABC transporter complex PstSACB involved in phosphate import. Responsible for energy coupling to the transport system. ATP + H2O + phosphate(out) = ADP + H(+) + 2 phosphate(in) The complex is composed of two ATP-binding proteins (PstB), two transmembrane proteins (PstC and PstA) and a solute-binding protein (PstS). Belongs to the ABC transporter superfamily. Phosphate importer (TC 3.A.1.7) family. Extended N-terminus. Extended N-terminus.