Hemoglobin
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(heterotetramer, (aß)2)
Structure of human hemoglobin. The proteins a and ß subunits are in red and blue, and the iron-containing heme groups in green. From PDB: 1GZX? Proteopedia Hemoglobin
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Protein type
metalloprotein, globulin
Function
oxygen-transport
Cofactor(s)
heme (4)
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Subunit
name
Gene
Chromosomal
locus
Hb-a1
HBA1
Chr. 16 p13.3
Hb-a2
HBA2
Chr. 16 p13.3
Hb-ß
HBB
Chr. 11 p15.5
Hemoglobin (/'hi?m??glo?b?n, 'h?-, -mo?-/); also spelled haemoglobin and abbreviated Hb or Hgb, is the iron-containing oxygen-transport metalloprotein in the red blood cells of all vertebrates (with the exception of the fish family Channichthyidae) as well as the tissues of some invertebrates. Hemoglobin in the blood carries oxygen from the respiratory organs (lungs or gills) to the rest of the body (i.e. the tissues). There it releases the oxygen to permit aerobic respiration to provide energy to power the functions of the organism in the process called metabolism.In mammals, the protein makes up about 96% of the red blood cells' dry content (by weight), and around 35% of the total content (including water). Hemoglobin has an oxygen-binding capacity of 1.34 mL O2 per gram, which increases the total blood oxygen capacity seventy-fold compared to dissolved oxygen in blood. The mammalian hemoglobin molecule can bind (carry) up to four oxygen molecules.Hemoglobin is involved in the transport of other gases: It carries some of the body's respiratory carbon dioxide (about 20–25% of the total) as carbaminohemoglobin, in which CO2 is bound to the globin protein. The molecule also carries the important regulatory molecule nitric oxide bound to a globin protein thiol group, releasing it at the same time as oxygen.Hemoglobin is also found outside red blood cells and their progenitor lines. Other cells that contain hemoglobin include the A9 dopaminergic neurons in the substantia nigra, macrophages, alveolar cells, and mesangial cells in the kidney. In these tissues, hemoglobin has a non-oxygen-carrying function as an antioxidant and a regulator of iron metabolism.Hemoglobin and hemoglobin-like molecules are also found in many invertebrates, fungi, and plants. In these organisms, hemoglobins may carry oxygen, or they may act to transport and regulate other small molecules and ions such as carbon dioxide, nitric oxide, hydrogen sulfide and sulfide. A variant of the molecule, called leghemoglobin, is used to scavenge oxygen away from anaerobic systems, such as the nitrogen-fixing nodules of leguminous plants, before the oxygen can poison (deactivate) the system.
^ Jones, Daniel (2003) , Peter Roach, James Hartmann and Jane Setter, eds., English Pronouncing Dictionary, Cambridge: Cambridge University Press, ISBN 3-12-539683-2
^ "Hemoglobin". Dictionary.com Unabridged. Random House.
^ "Hemoglobin". Merriam-Webster Dictionary.
^ Maton, Anthea; Jean Hopkins; Charles William McLaughlin; Susan Johnson; Maryanna Quon Warner; David LaHart; Jill D. Wright (1993). Human Biology and Health. Englewood Cliffs, New Jersey, USA: Prentice Hall. ISBN 0-13-981176-1.
^ Sidell, Bruce; Kristin O'Brien (2006). "When bad things happen to good fish: the loss of hemoglobin and myoglobin expression in Antarctic icefishes". The Journal of Experimental Biology 209 (Pt 10): 1791–1802. doi:10.1242/jeb.02091. PMID 16651546.
^ Weed, Robert I.; Reed, Claude F.; Berg, George (1963). "Is hemoglobin an essential structural component of human erythrocyte membranes?". J Clin Invest. 42 (4): 581–8. doi:10.1172/JCI104747. PMC 289318. PMID 13999462.
^ Dominguez de Villota ED, Ruiz Carmona MT, Rubio JJ, de Andrés S (1981). "Equality of the in vivo and in vitro oxygen-binding capacity of haemoglobin in patients with severe respiratory disease". Br J Anaesth 53 (12): 1325–8. doi:10.1093/bja/53.12.1325. PMID 7317251.
^ Costanzo, Linda S. (2007). Physiology. Hagerstwon, MD: Lippincott Williams & Wilkins. ISBN 0-7817-7311-3.
^ Patton, Kevin T. (2015-02-10). Anatomy and Physiology. Elsevier Health Sciences. ISBN 9780323316873.
^ Epstein, F. H.; Hsia, C. C. W. (1998). "Respiratory Function of Hemoglobin". New England Journal of Medicine 338 (4): 239–247. doi:10.1056/NEJM199801223380407. PMID 9435331.
^ Biagioli M, Pinto M, Cesselli D, et al. (2009). "Unexpected expression of alpha- and beta-globin in mesencephalic dopaminergic neurons and glial cells". Proc. Natl. Acad. Sci. U.S.A. 106 (36): 15454–9. doi:10.1073/pnas.0813216106. PMC 2732704. PMID 19717439.
^ Cite error: The named reference :0 was invoked but never defined (see the help page).
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