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MT000183

UniProt Annotations

Entry Information

Gene Name	cytochrome b5 reductase 3
Protein Entry
UniProt ID
Species	Human

Comments

Comment type	Description
Alternative Products	Event=Alternative promoter usage, Alternative splicing; Named isoforms=3; Name=1; Synonyms=M; IsoId=P00387-1; Sequence=Displayed; Name=2; Synonyms=S; IsoId=P00387-2; Sequence=VSP_010200; Name=3; IsoId=P00387-3; Sequence=VSP_042827; Note=No experimental confirmation available.;
Catalytic Activity	NADH + 2 ferricytochrome b5 = NAD(+) + H(+) + 2 ferrocytochrome b5.
Cofactor	Name=FAD; Xref=ChEBI:CHEBI:57692;
Disease	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. {ECO:0000269\|PubMed:10807796, ECO:0000269\|PubMed:12393396, ECO:0000269\|PubMed:1400360, ECO:0000269\|PubMed:15622768, ECO:0000269\|PubMed:1707593, ECO:0000269\|PubMed:1898726, ECO:0000269\|PubMed:7718898, ECO:0000269\|PubMed:8119939, ECO:0000269\|PubMed:9695975, ECO:0000269\|PubMed:9886302}. Note=The disease is caused by mutations affecting the gene represented in this entry.
Function	Desaturation and elongation of fatty acids, cholesterol biosynthesis, drug metabolism, and, in erythrocyte, methemoglobin reduction.
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.
Similarity	Belongs to the flavoprotein pyridine nucleotide cytochrome reductase family. {ECO:0000305}.
Similarity	Contains 1 FAD-binding FR-type domain. {ECO:0000255\|PROSITE-ProRule:PRU00716}.
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.
Subunit	Component of a complex composed of cytochrome b5, NADH- cytochrome b5 reductase (CYB5R3) and MOSC2. {ECO:0000250}.
Tissue Specificity	Isoform 2 is expressed at late stages of erythroid maturation.
Web Resource	Name=NIEHS-SNPs; URL="http://egp.gs.washington.edu/data/dia1/";