ID:NB5R3_HUMAN DESCRIPTION: RecName: Full=NADH-cytochrome b5 reductase 3; Short=B5R; Short=Cytochrome b5 reductase; EC=1.6.2.2; AltName: Full=Diaphorase-1; Contains: RecName: Full=NADH-cytochrome b5 reductase 3 membrane-bound form; Contains: RecName: Full=NADH-cytochrome b5 reductase 3 soluble form; FUNCTION: Desaturation and elongation of fatty acids, cholesterol biosynthesis, drug metabolism, and, in erythrocyte, methemoglobin reduction. CATALYTIC ACTIVITY: NADH + 2 ferricytochrome b5 = NAD(+) + H(+) + 2 ferrocytochrome b5. COFACTOR: FAD. SUBUNIT: Component of a complex composed of cytochrome b5, NADH- cytochrome b5 reductase (CYB5R3) and MOSC2 (By similarity). SUBCELLULAR LOCATION: Isoform 1: Endoplasmic reticulum membrane; Lipid-anchor; Cytoplasmic side. Mitochondrion outer membrane; Lipid-anchor; Cytoplasmic side. SUBCELLULAR LOCATION: Isoform 2: Cytoplasm. Note=Produces the soluble form found in erythrocytes. TISSUE SPECIFICITY: Isoform 2 is expressed at late stages of erythroid maturation. POLYMORPHISM: Ser-117 seems to only be found in persons of African origin. The allele frequency is 0.23 in African Americans. It was not found in Caucasians, Asians, Indo-Aryans, or Arabs. There seems to be no effect on the enzyme activity. DISEASE: Defects in CYB5R3 are the cause of methemoglobinemia CYB5R3-related (METHB-CYB5R3) [MIM:250800]. 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. SIMILARITY: Belongs to the flavoprotein pyridine nucleotide cytochrome reductase family. SIMILARITY: Contains 1 FAD-binding FR-type domain. WEB RESOURCE: Name=NIEHS-SNPs; URL="http://egp.gs.washington.edu/data/dia1/";
The RNAfold program from the Vienna RNA Package is used to perform the secondary structure predictions and folding calculations. The estimated folding energy is in kcal/mol. The more negative the energy, the more secondary structure the RNA is likely to have.
ModBase Predicted Comparative 3D Structure on P00387
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Orthologous Genes in Other Species
Orthologies between human, mouse, and rat are computed by taking the best BLASTP hit, and filtering out non-syntenic hits. For more distant species reciprocal-best BLASTP hits are used. Note that the absence of an ortholog in the table below may reflect incomplete annotations in the other species rather than a true absence of the orthologous gene.
Biological Process: GO:0006629 lipid metabolic process GO:0006694 steroid biosynthetic process GO:0006695 cholesterol biosynthetic process GO:0008015 blood circulation GO:0008202 steroid metabolic process GO:0008203 cholesterol metabolic process GO:0016126 sterol biosynthetic process GO:0019852 L-ascorbic acid metabolic process GO:0043312 neutrophil degranulation GO:0055114 oxidation-reduction process
US Server
Sequence and Links to Tools and Databases 
Common Gene Haplotype Alleles 
