0000000000292890
AUTHOR
Mark Haberkamp
Neuroglobin and cytoglobin in search of their role in the vertebrate globin family
Neuroglobin and cytoglobin are two recent additions to the family of heme-containing respiratory proteins of man and other vertebrates. Here, we review the present state of knowledge of the structures, ligand binding kinetics, evolution and expression patterns of these two proteins. These data provide a first glimpse into the possible physiological roles of these globins in the animal's metabolism. Both, neuroglobin and cytoglobin are structurally similar to myoglobin, although they contain distinct cavities that may be instrumental in ligand binding. Kinetic and structural studies show that neuroglobin and cytoglobin belong to the class of hexa-coordinated globins with a biphasic ligand-bi…
A novel and ancient group of type I keratins with members in bichir, sturgeon and gar
Abstract 1. Background Vertebrate epithelial cells typically express a specific set of keratins. In teleosts, keratins are also present in a variety of mesenchymal cells, which usually express vimentin. Significantly, our previous studies revealed that virtually all known teleost keratins evolved independently from those present in terrestrial vertebrates. To further elucidate the evolutionary scenario that led to the large variety of keratins and their complex expression patterns in present day teleosts, we have investigated their presence in bichir, sturgeon and gar. 2. Results We have discovered a novel group of type I keratins with members in all three of these ancient ray-finned fish, …
Zebrafish Reveals Different and Conserved Features of Vertebrate Neuroglobin Gene Structure, Expression Pattern, and Ligand Binding
Neuroglobin has been identified as a respiratory protein that is primarily expressed in the mammalian nervous system. Here we present the first detailed analysis of neuroglobin from a non-mammalian vertebrate, the zebrafish Danio rerio. The zebrafish neuroglobin gene reveals a mammalian-type exon-intron pattern in the coding region (B12.2, E11.0, and G7.0), plus an additional 5'-non-coding exon. Similar to the mammalian neuroglobin, the zebrafish protein displays a hexacoordinate deoxy-binding scheme. Flash photolysis kinetics show the competitive binding on the millisecond timescale of external ligands and the distal histidine, resulting in an oxygen affinity of 1 torr. Western blotting, i…
Neuroglobin, cytoglobin, and a novel, eye-specific globin from chicken
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…
Neuroglobin mRNA expression after transient global brain ischemia and prolonged hypoxia in cell culture.
Abstract Neuroglobin is a nerve-specific respiratory protein that has been proposed to play an important role in the protection of brain neurons from ischemic and hypoxic injuries. Here, we investigated the regulation of neuroglobin expression after transient global ischemia in the rat brain using mRNA in situ hybridization and under hypoxic stress in cultured neuronal cell lines (PC12, HN33) by quantitative RT-PCR. While neuroglobin mRNA expression was significantly enhanced in cell culture after severe prolonged hypoxia (0–1% O 2 for 24 h), we did not find any significant increases in neuroglobin mRNA levels in the rat brain after transient global ischemia. Vegf and Glut1 mRNAs showed inc…
Type I keratin cDNAs from the rainbow trout: independent radiation of keratins in fish
Five different type I keratins from a teleost fish, the rainbow trout Oncorhynchus mykiss, have been sequenced by cDNA cloning and identified at the protein level by peptide mass mapping using MALDI-MS. This showed that the entire range of type I keratins detected biochemically in this fish has now been sequenced. Three of the keratins are expressed in the epidermis (subtype Ie), whereas the other two occur in simple epithelia and mesenchymal cells (subtype Is). Among the Is keratins is an ortholog of human K18; the second Is polypeptide is clearly distinct from K18. We raised a new monoclonal antibody (F1F2, subclass IgG1) that specifically recognizes trout Is keratins, with negative react…
Type II keratin cDNAs from the rainbow trout: implications for keratin evolution.
From a teleost fish, the rainbow trout Oncorhynchus mykiss, we have cloned and sequenced cDNAs encoding five different type II keratins. The corresponding protein spots, as separated by 2D-PAGE of trout cytoskeletal preparations, have been identified by peptide mass mapping using MALDI mass spectrometry. Three of the sequenced keratins are expressed in the epidermis (subtype IIe), and two in simple epithelia and mesenchymal cells (subtype IIs). The IIs keratins are both orthologs of human K8. This leaves unsequenced only the trace component S3 of the biochemically established trout keratin catalog. A phylogenetic tree has been constructed from a multiple alignment of the rod domains of the …