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-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.
Hankeln
Thomas
T
Institute of Molecular Genetics, Johannes Gutenberg University of Mainz, D-55099 Mainz, Germany.
Ebner
Bettina
B
Fuchs
Christine
C
Gerlach
Frank
F
Haberkamp
Mark
M
Laufs
Tilmann L
TL
Roesner
Anja
A
Schmidt
Marc
M
Weich
Bettina
B
Wystub
Sylvia
S
Saaler-Reinhardt
Sigrid
S
Reuss
Stefan
S
Bolognesi
Martino
M
De Sanctis
Daniele
D
Marden
Michael C
MC
Kiger
Laurent
L
Moens
Luc
L
Dewilde
Sylvia
S
Nevo
Eviatar
E
Avivi
Aaron
A
Weber
Roy E
RE
Fago
Angela
A
Burmester
Thorsten
T
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
C000627265:CYGB protein, human; D000078842:Cytoglobin; D006420:Hemeproteins; D009419:Nerve Tissue Proteins; D000078787:Neuroglobin; D005914:Globins