PUMPS are mitochondrial transporter proteins that create proton leaks across the inner mitochondrial membrane, thus uncoupling oxidative phosphorylation. This leads to a decrease in the efficiency of oxidative phosphorylation and an increase in heat production. May be involved in protecting plant cells against oxidative stress damage (By similarity). Recombinant PUMP4, reconstituted into liposomes, transports a wide range of dicarboxylic acids including malate, oxaloacetate and succinate as well as phosphate, sulfate and thiosulfate. However, it is unknown if these transports are of any biological significance in vivo. Expressed in roots, leaves, stems and flowers. By cold stress. Belongs to the mitochondrial carrier (TC 2.A.29) family.