Cytoglobin

[5] Cytoglobin is a globin molecule ubiquitously expressed in all tissues and most notably utilized in marine mammals.

The predicted function of cytoglobin is the facilitation of oxygen among tissues that don't express myoglobin.

[9] Cytoglobin is a ubiquitously expressed hexacoordinate hemoglobin that may facilitate diffusion of oxygen through tissues, scavenge nitric oxide or reactive oxygen species, or serve a protective function during oxidative stress.

[12] In an oxidizing environment, a disulfide bond between Cys38 and Cys83 of the protein forms and causes a conformational change to move HisE7 out of the way, allowing oxygen to bind.

[11] CYGB expression can be used as a specific marker with which hepatic stellate cells can be distinguished from portal myofibroblasts in the damaged human liver.

Diagram of how the heme group in cytoglobin interacts with the surrounding amino acids of the globin protein. Normally, the iron is coordinated with histidine residues on both sides. The HisE7 must be dissociated in order for oxygen to bind.