Succinate Dehydrogenase [Ubiquinone] Cytochrome B Small Subunit, Mitochondrial (SDHD) Human Recombinant Protein

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 subunit D protein 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. [provided by RefSeq, Oct 2009]

SDHD: 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). Defects in SDHD are a cause of paragangliomas type 1 (PGL1). 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). 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). 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); 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). Cowden-like syndrome is a cancer predisposition syndrome associated with elevated risk for tumors of the breast, thyroid, kidney and uterus. Belongs to the CybS family.

Protein type: Mitochondrial; Membrane protein, multi-pass; Membrane protein, integral; Energy Metabolism - oxidative phosphorylation; Carbohydrate Metabolism - citrate (TCA) cycle

Chromosomal Location of Human Ortholog: 11q23

Cellular Component: mitochondrial envelope; mitochondrial respiratory chain complex II; mitochondrion; mitochondrial inner membrane; integral to membrane

Molecular Function: ubiquinone binding; electron carrier activity; metal ion binding; heme binding; succinate dehydrogenase activity

Biological Process: cellular metabolic process; tricarboxylic acid cycle

Disease: Paraganglioma And Gastric Stromal Sarcoma; Cowden Syndrome 3; Carcinoid Tumors, Intestinal; Paragangliomas 1; Pheochromocytoma