Involved in oxygen transport in the brain. Hexacoordinate globin, displaying competitive binding of oxygen or the distal His residue to the iron atom. Not capable of penetrating cell membranes. The deoxygenated form exhibits nitrite reductase activity inhibiting cellular respiration via NO-binding to cytochrome c oxidase. Involved in neuroprotection during oxidative stress. May exert its anti-apoptotic activity by acting to reset the trigger level of mitochondrial cytochrome c release necessary to commit the cells to apoptosis. Monomer. Homodimer and homotetramer; disulfide-linked (By similarity). Interacts with 14-3-3. Predominantly expressed in brain, the strongest expression is seen in the frontal lobe, the subthalamic nucleus and the thalamus. A redox disulfide bond regulates the heme pocket coordination and the rate of nitrite reduction to NO. Phosphorylated in vitro by ERK1, ERK2 and PKA, and in vivo during hypoxia. Phosphorylation increases nitrite reductase activity. Belongs to the globin family. Neuroglobin entry