呼吸鏈的復合物II，特別參與琥珀酸的氧化，攜帶電子從FADH到COQ。復合物由四個核編碼亞單位組成，并定位于線粒體內膜。鐵硫亞單位高度保守，包含三個富含半胱氨酸的簇，這些簇可能包含酶的鐵硫中心。該基因的零星和家族性突變導致副神經節瘤和嗜鉻細胞瘤，并支持線粒體功能障礙和腫瘤發生之間的聯系。
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.