呼吸链的复合物II，特别参与琥珀酸的氧化，携带电子从FADH到COQ。复合物由四个核编码亚单位组成，并定位于线粒体内膜。铁硫亚单位高度保守，包含三个富含半胱氨酸的簇，这些簇可能包含酶的铁硫中心。该基因的零星和家族性突变导致副神经节瘤和嗜铬细胞瘤，并支持线粒体功能障碍和肿瘤发生之间的联系。
Complex II of the respiratory chain, which is specifically involved in the oxidation of succinate, carries electrons from FADH to CoQ. The complex is composed of four nuclear-encoded subunits and is localized in the mitochondrial inner membrane. The iron-sulfur subunit is highly conserved and contains three cysteine-rich clusters which may comprise the iron-sulfur centers of the enzyme. Sporadic and familial mutations in this gene result in paragangliomas and pheochromocytoma, and support a link between mitochondrial dysfunction and tumorigenesis.