Functions in inorganic phosphate uptake, a phosphate-binding protein, although probably not the main uptake protein under phosphate starvation (By similarity). Part of the ABC transporter complex PstSACB involved in phosphate import (Probable). A host TLR2 agonist (toll-like receptor), requires both host TLR1 and TLR2 as coreceptors. The complex is composed of two ATP-binding proteins (PstB), two transmembrane proteins (PstC and PstA) and a solute-binding protein (PstS). Present on the cell surface. By phosphate starvation (at protein level). Belongs to the PstS family.