title: Neuroglobin and cytoglobin in search of their role in the vertebrate globin family.
abstract: 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-binding kinetics. Nevertheless, their oxygen affinities resemble that of myoglobin. While neuroglobin is evolutionarily related to the invertebrate nerve-globins, cytoglobin shares a more recent common ancestry with myoglobin. Neuroglobin expression is confined mainly to brain and a few other tissues, with the highest expression observed in the retina. Present evidence points to an important role of neuroglobin in neuronal oxygen homeostasis and hypoxia protection, though other functions are still conceivable. Cytoglobin is predominantly expressed in fibroblasts and related cell types, but also in distinct nerve cell populations. Much less is known about its function, although in fibroblasts it might be involved in collagen synthesis.
authors.affiliation: Institute of Molecular Genetics, Johannes Gutenberg University of Mainz, D-55099 Mainz, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Hankeln
authors.forename: Bettina
authors.initials: B
authors.lastname: Ebner
authors.forename: Christine
authors.initials: C
authors.lastname: Fuchs
authors.forename: Frank
authors.initials: F
authors.lastname: Gerlach
authors.forename: Mark
authors.initials: M
authors.lastname: Haberkamp
authors.forename: Tilmann L
authors.initials: TL
authors.lastname: Laufs
authors.forename: Anja
authors.initials: A
authors.lastname: Roesner
authors.forename: Marc
authors.initials: M
authors.lastname: Schmidt
authors.forename: Bettina
authors.initials: B
authors.lastname: Weich
authors.forename: Sylvia
authors.initials: S
authors.lastname: Wystub
authors.forename: Sigrid
authors.initials: S
authors.lastname: Saaler-Reinhardt
authors.forename: Stefan
authors.initials: S
authors.lastname: Reuss
authors.forename: Martino
authors.initials: M
authors.lastname: Bolognesi
authors.forename: Daniele
authors.initials: D
authors.lastname: De Sanctis
authors.forename: Michael C
authors.initials: MC
authors.lastname: Marden
authors.forename: Laurent
authors.initials: L
authors.lastname: Kiger
authors.forename: Luc
authors.initials: L
authors.lastname: Moens
authors.forename: Sylvia
authors.initials: S
authors.lastname: Dewilde
authors.forename: Eviatar
authors.initials: E
authors.lastname: Nevo
authors.forename: Aaron
authors.initials: A
authors.lastname: Avivi
authors.forename: Roy E
authors.initials: RE
authors.lastname: Weber
authors.forename: Angela
authors.initials: A
authors.lastname: Fago
authors.forename: Thorsten
authors.initials: T
authors.lastname: Burmester
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000078842:Cytoglobin; D005786:Gene Expression Regulation; D005914:Globins / Q000737:chemistry / Q000145:classification / Q000235:genetics / Q000378:metabolism; D006420:Hemeproteins / Q000737:chemistry / Q000145:classification / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000145:classification / Q000235:genetics / Q000378:metabolism; D000078787:Neuroglobin; D010802:Phylogeny; D011487:Protein Conformation; D016415:Sequence Alignment
chemical_list: C000627265:CYGB protein, human; D000078842:Cytoglobin; D006420:Hemeproteins; D009419:Nerve Tissue Proteins; D000078787:Neuroglobin; D005914:Globins