Involved in D-galactonate metabolism (PubMed:211976, PubMed:30455279). Catalyzes the proton-dependent uptake of galactonate into the cell (PubMed:31083648). D-galactonate(in) + H(+)(in) = D-galactonate(out) + H(+)(out) Uptake is inhibited by the proton ionophore nigericin, which dissipates the proton gradient, and by the potassium ionophore valinomycin, which dissipates the membrane potential. Part of the dgoRKADT operon, which encodes proteins for the metabolism of D-galactonate (PubMed:211976, PubMed:30455279). Negatively regulated by DgoR (PubMed:30455279). Expression is induced in the presence of D-galactonate (PubMed:30455279). Major conformational changes and local movement around the substrate site occur to accommodate substrate for transport (PubMed:31083648). Active transport requires reversible protonation of both Asp-31 and Glu-118 (PubMed:31083648). Deletion mutant cannot grow on D-galactonate. The exact stoichiometry of cotransport is not determined and could be greater than 1. Belongs to the major facilitator superfamily. Phthalate permease family. Extended N-terminus.