MITOCHONDRIAL COMPLEX II (SUCCINATE DEHYDROGENASE) SUBUNITS
Species
D. melanogaster
Symbol
MCII-SDH
FlyBase ID
FBgg0000485
Date last reviewed
2025-10-21
Number of members
7
Description
Description
The succinate dehydrogenase complex is unique in that it functions in both the tricarboxylic acid (TCA) cycle and the electron transport chain (ETC), wherein it is referred to as Complex II. It is a heterotetrameric protein complex that is anchored to the inner mitochondrial membrane by two integral membrane proteins, Sdh3 (SDHC) and Sdh4 (SDHD). This Sdh3/Sdh4 dimer binds the peripheral membrane protein Sdh2 (SDHB), which tethers the Sdh1 (SDHA) subunit to the complex. Sdh1 harbors a covalently bound FAD cofactor that is required for the oxidation of succinate to fumarate in the TCA cycle. The two electrons that result from succinate oxidation are channeled through the three iron-sulfur clusters in Sdh2 to ubiquinone, which interacts with the complex via the Sdh3/Sdh4 membrane anchor, and thereby reduce it to ubiquinol as part of the ETC. (Adapted from PMID:24954416 and PMID:37490987.)
Notes on Group
Three subunits of this complex are encoded by paralogous genes in D. melanogaster: SdhA and SdhAL; SdhB and SdhBL; SdhC and SdhCL. In each case, the first gene has widespread expression, whereas the second copy (the one with 'L' in the symbol) is expressed specifically in the testis.
