<p>This entry represents a domain with a spectrin-repeat-like fold consisting of three helices in a closed bundle with a left-handed twist. This domain is found in the succinate dehydrogenase/fumarate reductase oxidoreductase family of proteins, such as:</p><p> <ul> <li>L-aspartate oxidase (<db_xref db="EC" dbkey="1.4.3.16"/>), a flavoenzyme component of the bacterial quinolinate synthase system that catalyses the conversion of L-aspartate to oxaloacetate, the first step in the de novo biosynthesis of NAD+ [<cite idref="PUB00026780"/>, <cite idref="PUB00023955"/>].</li> </ul> </p><p> <ul> <li>Fumarate reductase, which is part of the quinol-fumarate reductase (QFR) respiratory complex that catalyses the terminal step of anaerobic respiration when fumarate acts as the terminal electron acceptor [<cite idref="PUB00013184"/>].</li> </ul> </p><p> <ul> <li>Succinate dehydrogenase (SQR; <db_xref db="EC" dbkey="1.3.5.1"/>), an iron-sulphur flavoenzyme from bacteria that is analogous to the mitochondrial respiratory complex II, forming part of the electron transport pathway from the electron acceptor (succinate) to the terminal donor (ubiquinone) [<cite idref="PUB00015752"/>].</li> </ul> </p><p> <ul> <li> Adenylylsulphate reductase A subunit (<db_xref db="EC" dbkey="1.8.4"/>), an iron-sulphur flavoenzyme that catalyses the reversible reduction of adenosine-5'-phosphate (APS) to sulphite and AMP [<cite idref="PUB00026455"/>].</li> </ul> </p> Fumarate reductase/succinate dehydrogenase flavoprotein-like, C-terminal