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Cytoglobin

From Wikipedia, the free encyclopedia

CYGB
Identifiers
AliasesCYGB, HGB, STAP, cytoglobin
External IDsOMIM: 608759; MGI: 2149481; HomoloGene: 12706; GeneCards: CYGB; OMA:CYGB - orthologs
Available structures
PDBOrtholog search: PDBe RCSB
Enzyme activity
EC #BRENDAExPASyKEGGMetaCyc
1.15.1.1↗↗↗↗
Orthologs
SpeciesHumanMouse
Entrez

114757

114886

Ensembl

ENSG00000161544

ENSMUSG00000020810

UniProt

Q8WWM9

Q9CX80

RefSeq (mRNA)

NM_134268

NM_030206

RefSeq (protein)

NP_599030

NP_084482

Location (UCSC)Chr 17: 76.53 – 76.55 MbChr 11: 116.54 – 116.55 Mb
PubMed search[3][4]
Wikidata
View/Edit HumanView/Edit Mouse

Cytoglobin is the protein product of CYGB, a human and mammalian gene.[5]

Cytoglobin is a globin molecule ubiquitously expressed in all tissues and most notably utilized in marine mammals. It was discovered in 2001[6] in hepatic stellate cells during liver fibrosis. Thus, it was originally called "stellate cell activated protein" or STAP.[7] It received its current name in 2002.[8] It is thought to help in the distribution and storage of oxygen as well as protect against hypoxia by scavenging reactive oxygen species . The predicted function of cytoglobin is the facilitation of oxygen among tissues that don't express myoglobin.[9]

Function

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Cytoglobin is a ubiquitously expressed hexacoordinate hemoglobin that may facilitate diffusion of oxygen through tissues, scavenge nitric oxide or reactive oxygen species, or serve a protective function during oxidative stress.[5][10]

Structure

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Cytoglobin has 30-40% sequence homology with myoglobin, and has a similar oxygen binding affinity. One of the major differences is the presence of a 20 amino acids extension at both the n and c terminus.[11]

Cytoglobin is a hexacoordinate heme protein. The heme iron in coordinated with histidine residues on both sides, HisF8 and HisE7. The HisE7 is considered to be an "endogenous ligand." In order for oxygen or another gaseous ligand to bind, the HisE7 must dissociate from the iron, making the binding kinetics relatively slow.[12]

Diagram of how the heme group in cytoglobin interacts with the surrounding amino acids of the globin protein. Normally, the iron is coordinated with histidine residues on both sides. The HisE7 must be dissociated in order for oxygen to bind.

In an oxidizing environment, a disulfide bond between Cys38 and Cys83 of the protein forms and causes a conformational change to move HisE7 out of the way, allowing oxygen to bind. Thus, oxygen binding is dependent on the redox state of the tissue.[11]

Applications

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CYGB expression can be used as a specific marker with which hepatic stellate cells can be distinguished from portal myofibroblasts in the damaged human liver.[13]

References

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  1. 1 2 3 GRCh38: Ensembl release 89: ENSG00000161544 – Ensembl, May 2017
  2. 1 2 3 GRCm38: Ensembl release 89: ENSMUSG00000020810 – Ensembl, May 2017
  3. ↑ "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  4. ↑ "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  5. 1 2 "Entrez Gene: CYGB cytoglobin".
  6. ↑ Kawada N, Kristensen DB, Asahina K, Nakatani K, Minamiyama Y, Seki S, et al. (July 2001). "Characterization of a stellate cell activation-associated protein (STAP) with peroxidase activity found in rat hepatic stellate cells". The Journal of Biological Chemistry. 276 (27): 25318–25323. doi:10.1074/jbc.M102630200. PMID 11320098.
  7. ↑ Pesce A, Bolognesi M, Bocedi A, Ascenzi P, Dewilde S, Moens L, et al. (December 2002). "Neuroglobin and cytoglobin. Fresh blood for the vertebrate globin family". EMBO Reports. 3 (12): 1146–1151. doi:10.1093/embo-reports/kvf248. PMC 1308314. PMID 12475928.
  8. ↑ Burmester T, Ebner B, Weich B, Hankeln T (April 2002). "Cytoglobin: a novel globin type ubiquitously expressed in vertebrate tissues". Molecular Biology and Evolution. 19 (4): 416–421. doi:10.1093/oxfordjournals.molbev.a004096. PMID 11919282.
  9. ↑ "Why Diving Marine Mammals Resist Brain Damage from Low Oxygen". ScienceDaily. 20 December 2007.
  10. ↑ Trent JT, Hargrove MS (May 2002). "A ubiquitously expressed human hexacoordinate hemoglobin". The Journal of Biological Chemistry. 277 (22): 19538–19545. doi:10.1074/jbc.M201934200. PMID 11893755.
  11. 1 2 Keller TC, Lechauve C, Keller AS, Brooks S, Weiss MJ, Columbus L, et al. (April 2022). "The role of globins in cardiovascular physiology". Physiological Reviews. 102 (2): 859–892. doi:10.1152/physrev.00037.2020. PMC 8799389. PMID 34486392.
  12. ↑ Hankeln T, Ebner B, Fuchs C, Gerlach F, Haberkamp M, Laufs TL, et al. (January 2005). "Neuroglobin and cytoglobin in search of their role in the vertebrate globin family". Journal of Inorganic Biochemistry. Heme-diatomic interactions, Part 1. 99 (1): 110–119. doi:10.1016/j.jinorgbio.2004.11.009. PMID 15598495.
  13. ↑ Motoyama H, Komiya T, Thuy le TT, Tamori A, Enomoto M, Morikawa H, et al. (February 2014). "Cytoglobin is expressed in hepatic stellate cells, but not in myofibroblasts, in normal and fibrotic human liver". Laboratory Investigation; A Journal of Technical Methods and Pathology. 94 (2): 192–207. doi:10.1038/labinvest.2013.135. PMID 24296877.

Further reading

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