SDHA (Succinate Dehydrogenase Complex Subunit A) is the catalytic subunit of mitochondrial Complex II (succinate dehydrogenase, SDH), which functions in both the Krebs tricarboxylic acid cycle and the mitochondrial electron transport chain. SDHA plays critical roles in cellular energy metabolism, and its dysfunction has been implicated in Parkinson's disease, Leigh syndrome, and various cancers 1. [1]
SDHA encodes the flavoprotein subunit of succinate dehydrogenase, a heterotetrameric complex (SDHA-SDHB-SDHC-SDHD) embedded in the mitochondrial inner membrane. As the catalytic subunit, SDHA binds FAD and succinate, initiating electron transfer to ubiquinone. SDH functions as a tumor suppressor, and germline mutations cause hereditary paragangliomas and pheochromocytomas. [2]
| Property | Value | [3]
|----------|-------|
| Gene | SDHA |
| UniProt ID | P31040 |
| Molecular Weight | ~73 kDa |
| Structure | Heterotetramer (SDHA-SDHB-SDHC-SDHD) |
| Localization | Mitochondrial inner membrane |
| EC Number | 1.3.5.1 |
SDHA contains multiple functional domains 2:
The complete Complex II (SDH) consists of:
SDHA catalyzes the oxidation of succinate to fumarate in the Krebs cycle:
Succinate + FAD → Fumarate + FADH2
The electrons from FADH2 are transferred via the 2Fe-2S cluster to ubiquinone (CoQ), ultimately feeding into Complex III of the electron transport chain. SDH is the only enzyme that participates in both the Krebs cycle and ETC.
SDHA dysfunction is particularly relevant to Parkinson's disease 3:
SDHA mutations cause severe neonatal encephalopathy:
The study of Sdha Protein Succinate Dehydrogenase Complex Subunit A has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.
Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.