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.
