CYBRD1
Identifiers
Aliases	CYBRD1, CYB561A2, DCYTB, FRRS3, cytochrome b reductase 1
External IDs	OMIM: 605745 MGI: 2654575 HomoloGene: 69387 GeneCards: CYBRD1
Gene location (Human) Chr. Chromosome 2 (human)[1] Band 2q31.1 Start 171,522,247 bp[1] End 171,558,129 bp[1]
Gene location (Mouse) Chr. Chromosome 2 (mouse)[2] Band 2|2 C2 Start 70,948,267 bp[2] End 70,973,270 bp[2]
RNA expression pattern Bgee Top expressed in Achilles tendon Germinal epithelium parietal pleura jejunal mucosa synovial joint superficial temporal artery right coronary artery gastric mucosa pericardium Stromal cell of endometrium More reference expression data BioGPS n/a
Gene ontology Molecular function oxidoreductase activity, acting on metal ions oxidoreductase activity ferric-chelate reductase activity GO:0001948 protein binding metal ion binding Cellular component integral component of membrane brush border membrane plasma membrane extracellular exosome membrane lysosomal membrane Biological process cellular iron ion homeostasis response to iron ion Sources:Amigo / QuickGO
Orthologs
Species	Human	Mouse
Entrez	79901	73649
Ensembl	ENSG00000071967	ENSMUSG00000027015
UniProt	Q53TN4	Q925G2
RefSeq (mRNA)	NM_024843 NM_001127383 NM_001256909	NM_028593
RefSeq (protein)	NP_001120855 NP_001243838 NP_079119	NP_082869
Location (UCSC)	Chr 2: 171.52 – 171.56 Mb	Chr 2: 70.95 – 70.97 Mb
PubMed search	[3]	[4]
Wikidata
View/Edit Human View/Edit Mouse

Duodenal cytochrome B (Dcytb) also known as cytochrome b reductase 1 is an enzyme that in humans is encoded by the CYBRD1 gene.

Dcytb CYBRD1 was first identified as a ferric reductase enzyme which catalyzes the reduction of Fe³⁺ to Fe²⁺ required for dietary iron absorption in the duodenum of mammals.^[5] Dcytb mRNA and protein levels in the gut are increased by iron deficiency and hypoxia which acts to promote dietary iron absorption. The effect of iron deficiency and hypoxia on Dcytb levels are medicated via the HIF2 (Hypoxia inducible factor 2) transcription factor which binds to hypoxia response elements within the Dcytb promoter and increases transcription of the gene.^[6] DCYTB protein has also been found in other tissues, such as lung epithelial cells^[7] and in the plasma membrane of mature red blood cells of scorbutic species (unable to make ascorbate) such as human and guinea pig^[8] but not in other species which have retained the ability to synthesise ascorbate like mice and rat. This has led to the notion that Dcytb may have an additional role in ascorbate metabolism in scorbutic species. DCYTB protein has also been found in breast tissue (epithelial and myoepithelial cells) and high DCYTB levels are associated with a favourable prognosis in patients with breast cancer.^[9] A single nucleotide polymorphism (SNP) within the DCYTB promoter (SNP rs884409) which reduced functional DCYTB promoter activity was also associated with reduced serum ferrtin levels in a patient cohort with C282Y haemochromatosis.^[10]