<p>Dihydroorotate dehydrogenase (<db_xref db="EC" dbkey="1.3.3.1"/>) (DHOdehase) catalyzes the fourth step in the <i>de novo</i> biosynthesis of pyrimidine, the conversion of dihydroorotate into orotate. DHOdehase is a ubiquitous FAD flavoprotein. In bacteria (gene pyrD), DHOdease is located on the inner side of the cytosolic membrane. In some yeasts, such as in <taxon tax_id="4932">Saccharomyces cerevisiae</taxon> (gene URA1), it is a cytosolic protein while in other eukaryotes it is found in the mitochondria [<cite idref="PUB00004801"/>].</p>