Scientific background: |
Cytoglobin(CYGB), also called HGB or STAP, is a ubiquitously expressed hexacoordinate hemoglobin that may facilitate diffusion of oxygen through tissues, scavenge nitric oxide or other reactive oxygen species, or serve a protective function during oxidative stress. The cytoglobin gene is mapped on 17q25.1. The CYGB gene contains 4 exons and spans about 9 kb. Cytoglobin has many elements common to vertebrate globins, including invariant histidine residues, and the amino acids that form the heme pocket share similarity with pentacoordinate myoglobin. In contrast to the high oxygen affinities displayed by most hexacoordinate hemoglobins, the characteristics of CYGB indicate that it can facilitate oxygen transport. Because the oxygen affinity of CYGB is more similar to myoglobin than to neuroglobin, and the oxy form of CYGB resists autooxidation, CYGB is proposed to represent a tissue oxygen reservoir by Sawai et al. |
References: |
1. Asahina, K., Kawada, N., Kristensen, D. B., Nakatani, K., Seki, S., Shiokawa, M., Tateno, C., Obara, M., Yoshizato, K. Characterization of human stellate cell activation-associated protein and its expression in human liver. Biochim. Biophys. Acta 1577: 471-475, 2002.
2. Burmester, T., Ebner, B., Weich, B., Hankeln, T. Cytoglobin: a novel globin type ubiquitously expressed in vertebrate tissues. Molec. Biol. Evol. 19: 416-421, 2002.
3. Geuens, E., Brouns, I., Flamez, D., Dewilde, S., Timmermans, J.-P., Moens, L. A globin in the nucleus! J. Biol. Chem. 278: 30417-30420, 2003.
|