Myoglobin

Myoglobin (symbol Mb or MB) is an iron- and oxygen-binding protein found in the cardiac and skeletal muscle tissue of vertebrates in general and in almost all mammals.[5][6][7][8][9] Myoglobin is distantly related to hemoglobin. Compared to hemoglobin, myoglobin has a higher affinity for oxygen and does not have cooperative binding with oxygen like hemoglobin does.[8][10] In humans, myoglobin is only found in the bloodstream after muscle injury.[11][12][13]

MB
Available structures
PDBOrtholog search: PDBe RCSB
Identifiers
AliasesMB, PVALB, myoglobgin, myoglobin, Myoglobin
External IDsOMIM: 160000 MGI: 96922 HomoloGene: 3916 GeneCards: MB
Orthologs
SpeciesHumanMouse
Entrez
Ensembl
UniProt
RefSeq (mRNA)

NM_005368
NM_203377
NM_203378
NM_001362846

NM_001164047
NM_001164048
NM_013593

RefSeq (protein)

NP_001157519
NP_001157520
NP_038621

Location (UCSC)Chr 22: 35.61 – 35.64 MbChr 15: 76.9 – 76.93 Mb
PubMed search[3][4]
Wikidata
View/Edit HumanView/Edit Mouse

High concentrations of myoglobin in muscle cells allow organisms to hold their breath for a longer period of time. Diving mammals such as whales and seals have muscles with particularly high abundance of myoglobin.[13] Myoglobin is found in Type I muscle, Type II A, and Type II B; although many texts consider myoglobin not to be found in smooth muscle, this has proved erroneous: there is also myoglobin in smooth muscle cells.[14]

Myoglobin was the first protein to have its three-dimensional structure revealed by X-ray crystallography.[15] This achievement was reported in 1958 by John Kendrew and associates.[16] For this discovery, Kendrew shared the 1962 Nobel Prize in chemistry with Max Perutz.[17][18] Despite being one of the most studied proteins in biology, its physiological function is not yet conclusively established: mice genetically engineered to lack myoglobin can be viable and fertile, but show many cellular and physiological adaptations to overcome the loss. Through observing these changes in myoglobin-depleted mice, it is hypothesised that myoglobin function relates to increased oxygen transport to muscle, and to oxygen storage; as well, it serves as a scavenger of reactive oxygen species.[19]

In humans, myoglobin is encoded by the MB gene.[20]

Myoglobin can take the forms oxymyoglobin (MbO2), carboxymyoglobin (MbCO), and metmyoglobin (met-Mb), analogously to hemoglobin taking the forms oxyhemoglobin (HbO2), carboxyhemoglobin (HbCO), and methemoglobin (met-Hb).[21]


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