Mediates the exchange of external hexose 6-phosphate and internal inorganic phosphate. Can transport glucose-6-phosphate, fructose-6-phosphate and mannose-6-phosphate. Also catalyzes the neutral exchange of internal and external phosphate. Reaction is unaffected by the ionophores valinomycin, valinomycin plus nigericin, and carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP). Monomer. Expression is induced by external glucose-6-phosphate through the UhpABC signaling cascade. Belongs to the major facilitator superfamily. Organophosphate:Pi antiporter (OPA) (TC 2.A.1.4) family.