background:
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. SDHD is one of two integral membrane proteins anchoring the complex to the matrix side of the membrane. Mutations in SDHD have been linked to hereditary paraganglioma.
Function:
Membrane-anchoring subunit of succinate dehydrogenase (SDH) that is involved in complex II of the mitochondrial electron transport chain and is responsible for transferring electrons from succinate to ubiquinone (coenzyme Q) (By similarity).
Subunit:
Component of complex II composed of four subunits: the flavoprotein (FP) SDHA, iron-sulfur protein (IP) SDHB, and a cytochrome b560 composed of SDHC and SDHD.
Subcellular Location:
Mitochondrion inner membrane; Multi-pass membrane protein.
DISEASE:
Defects in SDHD are a cause of paragangliomas type 1 (PGL1) [MIM:33600]. A neural crest tumor usually derived from the chromoreceptor tissue of a paraganglion. PGL1 is a rare autosomal dominant disorder which is characterized by the development of mostly benign, highly vascular, slowly growing tumors in the head and neck. In the head and neck region, the carotid body is the largest of all paraganglia and is also the most common site of the tumors.
Defects in SDHD are a cause of susceptibility to pheochromocytoma (PCC) [MIM:171300]. A catecholamine-producing tumor of chromaffin tissue of the adrenal medulla or sympathetic paraganglia. The cardinal symptom, reflecting the increased secretion of epinephrine and norepinephrine, is hypertension, which may be persistent or intermittent.
Defects in SDHD may be a cause of susceptibility to intestinal carcinoid tumor (ICT) [MIM:11980]. A yellow, well-differentiated, circumscribed tumor that arises from enterochromaffin cells in the small intestine or, less frequently, in other parts of the gastrointestinal tract.
Defects in SDHD are a cause of paraganglioma and gastric stromal sarcoma (PGGSS) [MIM:606864]; also called Carney-Stratakis syndrome. Gastrointestinal stromal tumors may be sporadic or inherited in an autosomal dominant manner, alone or as a component of a syndrome associated with other tumors, such as in the context of neurofibromatosis type 1 (NF1). Patients have both gastrointestinal stromal tumors and paragangliomas. Susceptibility to the tumors was inherited in an apparently autosomal dominant manner, with incomplete penetrance.
Defects in SDHD are a cause of Cowden-like syndrome (CWDLS) [MIM:612359]. Cowden-like syndrome is a cancer predisposition syndrome associated with elevated risk for tumors of the breast, thyroid, kidney and uterus.
Similarity:
Belongs to the CybS family.
Database links:
UniProtKB/Swiss-Prot: O14521.1
Important Note:
This product as supplied is intended for research use only, not for use in human, therapeutic or diagnostic applications.
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