High-affinity sodium/citrate cotransporter that mediates citrate entry into cells. Transports citrate in a Na(+)-dependent manner, transport process is electrogenic and recognizes the trivalent form of citrate rather than the divalent form. Although citrate is its main substrate, other intermediates of the citric acid cycle, such as succinate, fumarate, malate, oxaloacetate and alpha-ketoglutarate can serve as substrates but with a much lower affinity compared to citrate. Shows a substrate sensitivity in the order of citrate > malate ~ alpha-ketoglutarate > succinate ~ fumarate > oxaloacetate ~ isocitrate. Shows substantial citrate transporter activity when sodium ions are replaced by either potassium or choline ions. Transport activity is potentiated by lithium ions in the presence of low concentrations of citrate but is inhibited by lithium ions in the presence of high concentrations of citrate. Involved in the regulation of citrate levels in the brain.