Search results for "cytoglobin"
showing 8 items of 38 documents
Coupling of the heme and an internal disulfide bond in human neuroglobin
2004
Neuroglobin displays a hexacoordination His-Fe-His in the absence of external ligands such as oxygen. The observed oxygen affinity therefore depends on the binding rates of both oxygen and the competing distal histidine. Furthermore, the binding properties depend on the presence of an internal disulfide bond. In the case of human neuroglobin, cysteines at positions CD7 and D5 are sufficiently close to form an internal disulfide bond. For cytoglobin, the cysteine residues at positions A7 and GH4 may also form a disulfide bond. Mass spectrometry, ligand binding, and thiol accessibility studies were used to study the role influence of these disulfide bonds. Mutation of specific cysteines, or r…
Cerebral expression of neuroglobin and cytoglobin after deep hypothermic circulatory arrest in neonatal piglets
2010
Deep hypothermic circulatory arrest (DHCA) is used in corrective cardiac surgery for complex congenital heart disease. Endogenous protective mechanisms may be responsible for the prevention of brain damage after hypothermic ischemia. Neuroglobin and cytoglobin are expressed in brain cells and appear to modulate hypoxic-ischemic brain injury. However, their neuroprotective potency is still not understood. Thus the aim of this study was to detect the influence exerted by DHCA on their expression.The effects of DHCA were analyzed in a neonatal piglet model with cardiopulmonary bypass, DHCA of 60 and 120 min and subsequent reperfusion of 6h. Complete histological analysis and changes in the mRN…
Function and evolution of vertebrate globins.
2014
Globins are haem-proteins that bind O2 and thus play an important role in the animal's respiration and oxidative energy production. However, globins may also have other functions such as the decomposition or production of NO, the detoxification of reactive oxygen species or intracellular signalling. In addition to the well-investigated haemoglobins and myoglobins, genome sequence analyses have led to the identification of six further globin types in vertebrates: androglobin, cytoglobin, globin E, globin X, globin Y and neuroglobin. Here, we review the present state of knowledge on the functions, the taxonomic distribution and evolution of vertebrate globins, drawing conclusions about the fu…
Neuroglobin, cytoglobin, and a novel, eye-specific globin from chicken
2004
Neuroglobin and cytoglobin are two recently discovered respiratory proteins of vertebrates. Here we report the first identification and expression analyses of these proteins in bird species. Neuroglobin from the domestic chicken Gallus gallus differs in approximately 30% from the mammalian proteins, but its genome structure shows the conservation of the B12.2, E11.0, and G7.0 intron positions. The chicken cytoglobin protein is shorter than the mammalian orthologs, from which it differs overall by approximately 25%, due to the absence of the C-terminal exon in the gene. Comparison of chicken and mammalian gene order shows that neuroglobin and cytoglobin are located on conserved syntenic chro…
Duplicated cytoglobin genes in teleost fishes
2005
Cytoglobin is a recently discovered myoglobin-related O2-binding protein of vertebrates with uncertain function. It occurs as single-copy gene in mammals. Here, we demonstrate the presence of two paralogous cytoglobin genes (Cygb-1 and Cygb-2) in the teleost fishes Danio rerio, Oryzias latipes, Tetraodon nigroviridis, and Takifugu rubripes. The globin-typical introns at positions B12.2 and G7.0 are conserved in both genes, whereas the C-terminal exon found in mammalian cytoglobin is absent in the fish genes. Phylogenetic analyses show that the two cytoglobin genes diverged early in teleost evolution. This is confirmed by gene synteny analyses, which suggest a large-scale duplication event. …
The nerve hemoglobin of the bivalve mollusc Spisula solidissima
2006
Abstract Members of the hemoglobin (Hb) superfamily are present in nerve tissue of several vertebrate and invertebrate species. In vertebrates they display hexacoordinate heme iron atoms and are typically expressed at low levels (μm). Their function is still a matter of debate. In invertebrates they have a hexa- or pentacoordinate heme iron, are mostly expressed at high levels (mm), and have been suggested to have a myoglobin-like function. The native Hb of the surf clam, Spisula solidissima, composed of 162 amino acids, does not show specific deviations from the globin templates. UV-visible and resonance Raman spectroscopy demonstrate a hexacoordinate heme iron. Based on the sequence analo…
Regulation and Role of Neuroglobin and Cytoglobin Under Hypoxia
2007
Neuroglobin (Ngb) and cytoglobin (Cygb) are two novel members of the globin superfamily that are ubiquitously present in vertebrates. Their exact physiological roles are still uncertain. Here we review the expression of Ngb and Cygb, with particular emphasis on their regulation and potential role under hypoxia. Ngb expression is confined to neurons and some endocrine tissues. At the subcellular level, Ngb is associated with the presence of mitochondria and thus linked to the oxidative metabolism. Hypoxia or ischemic insults most likely do not strongly increase Ngb levels in the rodent brain. This might be explained by the fact that most mammals are not adapted to low oxygen levels. In zebra…
Globins and hypoxia adaptation in the goldfish, Carassius auratus
2008
Goldfish (Carassius auratus) may survive in aquatic environments with low oxygen partial pressures. We investigated the contribution of respiratory proteins to hypoxia tolerance in C. auratus. We determined the complete coding sequence of hemoglobin α and β and myoglobin, as well as partial cDNAs from neuroglobin and cytoglobin. Like the common carp (Cyprinus carpio), C. auratus possesses two paralogous myoglobin genes that duplicated within the cyprinid lineage. Myoglobin is also expressed in nonmuscle tissues. By means of quantitative real-time RT-PCR, we determined the changes in mRNA levels of hemoglobin, myoglobin, neuroglobin and cytoglobin in goldfish exposed to prolonged hypoxia (48…