This takes place in two steps. Pyruvate carboxylase is a biotin-dependent mitochondrial enzyme that converts pyruvate to oxaloacetate in the presence of ATP and CO₂. This enzyme regulates gluconeogenesis. Oxaloacetate is synthesised in the mitochondrial matrix. It has to be transported to cytosol to be used in gluconeogenesis, where the rest of the pathway occurs. The reversible conversion of oxaloacetate to malate is catalysed by malate dehydrogenase, an enzyme present in both mitochondria and cytosol. In the cytosol, phosphoenol pyruvate carboxylase converts oxaloacetate to phosphoenol pyruvate.