Structural Biochemistry/Protein function/Additional Globins

The human genome sequence has revealed two new globins, neuroglobin and cytoglobin. These proteins are both monomeric, and resemble myoglobin more than hemoglobin. Neuroglobin is expressed in the brain and in the retina. Its roles include protecting neural tissues from hypoxia, insufficient oxygenation of the blood or tissue. Cytoglobin is expressed throughout the body. Spectroscopy exhibits that the proximal and sital histidines are coordinated to iron in the deoxy form in both proteins. The distal histidine is displaced on oxygen binding.