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Antarctic Marine Biodiversity: Adaptations, Environments and Responses to Change
Published in S. J. Hawkins, A. J. Evans, A. C. Dale, L. B. Firth, I. P. Smith, Oceanography and Marine Biology, 2018
Recently the genes for neuroglobin (Cheng et al. 2009a,b, Boron et al. 2011, Giordano et al. 2012a) and cytoglobin (Shin et al. 2012) have been discovered in Antarctic fish. Neuroglobin is a 17-kDa monomeric hexa-coordinated hemoprotein with the classical globin folding pattern. It has a high oxygen affinity (in the range of typical myoglobin values (half saturation pressure P50 = 0.9–2.2 Torr (0.12–0.29 kPa))). Cytoglobin is a 21-kDa hemoprotein with the same globin folding pattern and oxygen affinity in the myoglobin-like range of 1 Torr (0.13 kPa). Antarctic fish neuroglobin and cytoglobin have been shown to bind oxygen and carbon monoxide reversibly. They also have high oxygen affinity, which is similar to that of human cytoglobin, but the high oxygen affinity means they are unlikely to be involved in oxygen transport (Giordano et al. 2015, Verde et al. 2011). Other globins, including globin X and Y, found in teleosts, have not been found so far in Antarctic fish (Giordano et al. 2015). Neuroglobin has been found in the haemoglobinless channichthyids, most of which also lack myoglobin. It has been hypothesised that their retention in this group is likely to be associated with protection of nervous tissues from nitrosative effects and oxidative damage to tissues in the oxygen-rich waters of the Southern Ocean (Giordano et al. 2015). One other way that the function and importance of cytoglobins has been studied is through their genes and gene expression.
Electron paramagnetic resonance of globin proteins – a successful match between spectroscopic development and protein research
Published in Molecular Physics, 2018
Sabine Van Doorslaer, Bert Cuypers
Finally, several different globins may co-exist in one species. The genome of the small nematode Caenorhabditis elegans codes for no less than 33 globins that are all transcribed [15]. For a long time, it was assumed that myo- and haemoglobin were the only globins present in humans (and in extension in mammals). However, in 2000, a hexacoordinate globin called neuroglobin was discovered in the human brain [16]. In 2001, another hexacoordinate globin, cytoglobin (Cygb), was reported to be expressed in most vertebrate tissues and organs [17]. Finally, a chimeric globin, androglobin (Adgb), was discovered in 2012 and is predominantly expressed in mammalian testes [18].