Tricarboxylate transport protein, mitochondrial

Tricarboxylate transport protein, mitochondrial, also known as tricarboxylate carrier protein and citrate transport protein (CTP), is a protein that in humans is encoded by the SLC25A1 gene. SLC25A1 belongs to the mitochondrial carrier gene family SLC25. High levels of the tricarboxylate transport protein are found in the liver, pancreas and kidney. Lower or no levels are present in the brain, heart, skeletal muscle, placenta and lung.

The tricarboxylate transport protein is located within the inner mitochondria membrane. It provides a link between the mitochondrial matrix and cytosol by transporting citrate through the impermeable inner mitochondrial membrane in exchange for malate from the cytosol. The citrate transported out of the mitochondrial matrix by the tricarboxylate transport protein is catalyzed by citrate lyase to acetyl CoA, the starting material for fatty acid biosynthesis, and oxaloacetate. As well, cytosolic NADPH + H⁺ necessary for fatty acid biosynthesis is generated in the reduction of oxaloacetate to malate and pyruvate by malate dehydrogenase and the malic enzyme. For these reasons, the tricarboxylate transport protein is considered to play a key role in fatty acid synthesis.