Cytochrome B5 Reductase 3 (CYB5R3) Human Recombinant Protein

This gene encodes cytochrome b5 reductase, which includes a membrane-bound form in somatic cells (anchored in the endoplasmic reticulum, mitochondrial and other membranes) and a soluble form in erythrocytes. The membrane-bound form exists mainly on the cytoplasmic side of the endoplasmic reticulum and functions in desaturation and elongation of fatty acids, in cholesterol biosynthesis, and in drug metabolism. The erythrocyte form is located in a soluble fraction of circulating erythrocytes and is involved in methemoglobin reduction. The membrane-bound form has both membrane-binding and catalytic domains, while the soluble form has only the catalytic domain. Alternate splicing results in multiple transcript variants. Mutations in this gene cause methemoglobinemias. [provided by RefSeq, Jan 2010]

CYB5R3: Desaturation and elongation of fatty acids, cholesterol biosynthesis, drug metabolism, and, in erythrocyte, methemoglobin reduction. Defects in CYB5R3 are the cause of methemoglobinemia CYB5R3-related (METHB-CYB5R3). A form of methemoglobinemia, a hematologic disease characterized by the presence of excessive amounts of methemoglobin in blood cells, resulting in decreased oxygen carrying capacity of the blood, cyanosis and hypoxia. There are two types of methemoglobinemia CYB5R3-related. In type 1, the defect affects the soluble form of the enzyme, is restricted to red blood cells, and causes well- tolerated methemoglobinemia. In type 2, the defect affects both the soluble and microsomal forms of the enzyme and is thus generalized, affecting red cells, leukocytes and all body tissues. Type 2 methemoglobinemia is associated with mental deficiency and other neurologic symptoms. Belongs to the flavoprotein pyridine nucleotide cytochrome reductase family. 3 isoforms of the human protein are produced by alternative promoter.

Protein type: Oxidoreductase; Carbohydrate Metabolism - amino sugar and nucleotide sugar; Mitochondrial; EC 1.6.2.2

Chromosomal Location of Human Ortholog: 22q13.2

Cellular Component: mitochondrial outer membrane; endoplasmic reticulum membrane; membrane; mitochondrion; hemoglobin complex; endoplasmic reticulum; mitochondrial inner membrane; cytoplasm; lipid particle

Molecular Function: FAD binding; cytochrome-b5 reductase activity; ADP binding; NAD binding; AMP binding

Biological Process: vitamin metabolic process; blood circulation; L-ascorbic acid metabolic process; cholesterol biosynthetic process; water-soluble vitamin metabolic process

Disease: Methemoglobinemia Due To Deficiency Of Methemoglobin Reductase