1v5h
From Proteopedia
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==Overview== | ==Overview== | ||
| - | Cytoglobin (Cgb), a newly discovered member of the vertebrate globin | + | Cytoglobin (Cgb), a newly discovered member of the vertebrate globin family, binds O(2) reversibly via its heme, as is the case for other mammalian globins (hemoglobin (Hb), myoglobin (Mb) and neuroglobin (Ngb)). While Cgb is expressed in various tissues, its physiological role is not clearly understood. Here, the X-ray crystal structure of wild type human Cgb in the ferric state at 2.4A resolution is reported. In the crystal structure, ferric Cgb is dimerized through two intermolecular disulfide bonds between Cys38(B2) and Cys83(E9), and the dimerization interface is similar to that of lamprey Hb and Ngb. The overall backbone structure of the Cgb monomer exhibits a traditional globin fold with a three-over-three alpha-helical sandwich, in which the arrangement of helices is basically the same among all globins studied to date. A detailed comparison reveals that the backbone structure of the CD corner to D helix region, the N terminus of the E-helix and the F-helix of Cgb resembles more closely those of pentacoordinated globins (Mb, lamprey Hb), rather than hexacoordinated globins (Ngb, rice Hb). However, the His81(E7) imidazole group coordinates directly to the heme iron as a sixth axial ligand to form a hexcoordinated heme, like Ngb and rice Hb. The position and orientation of the highly conserved residues in the heme pocket (Phe(CD1), Val(E11), distal His(E7) and proximal His(F8)) are similar to those of other globin proteins. Two alternative conformations of the Arg84(E10) guanidium group were observed, suggesting that it participates in ligand binding to Cgb, as is the case for Arg(E10) of Aplysia Mb and Lys(E10) of Ngb. The structural diversities and similarities among globin proteins are discussed with relevance to molecular evolutionary relationships. |
==About this Structure== | ==About this Structure== | ||
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[[Category: Kawada, N.]] | [[Category: Kawada, N.]] | ||
[[Category: Makino, M.]] | [[Category: Makino, M.]] | ||
| - | [[Category: RSGI, RIKEN | + | [[Category: RSGI, RIKEN Structural Genomics/Proteomics Initiative.]] |
[[Category: Sawai, H.]] | [[Category: Sawai, H.]] | ||
[[Category: Shiro, Y.]] | [[Category: Shiro, Y.]] | ||
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[[Category: structural genomics]] | [[Category: structural genomics]] | ||
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 15:31:41 2008'' |
Revision as of 13:31, 21 February 2008
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Crystal Structure of Human Cytoglobin (Ferric Form)
Overview
Cytoglobin (Cgb), a newly discovered member of the vertebrate globin family, binds O(2) reversibly via its heme, as is the case for other mammalian globins (hemoglobin (Hb), myoglobin (Mb) and neuroglobin (Ngb)). While Cgb is expressed in various tissues, its physiological role is not clearly understood. Here, the X-ray crystal structure of wild type human Cgb in the ferric state at 2.4A resolution is reported. In the crystal structure, ferric Cgb is dimerized through two intermolecular disulfide bonds between Cys38(B2) and Cys83(E9), and the dimerization interface is similar to that of lamprey Hb and Ngb. The overall backbone structure of the Cgb monomer exhibits a traditional globin fold with a three-over-three alpha-helical sandwich, in which the arrangement of helices is basically the same among all globins studied to date. A detailed comparison reveals that the backbone structure of the CD corner to D helix region, the N terminus of the E-helix and the F-helix of Cgb resembles more closely those of pentacoordinated globins (Mb, lamprey Hb), rather than hexacoordinated globins (Ngb, rice Hb). However, the His81(E7) imidazole group coordinates directly to the heme iron as a sixth axial ligand to form a hexcoordinated heme, like Ngb and rice Hb. The position and orientation of the highly conserved residues in the heme pocket (Phe(CD1), Val(E11), distal His(E7) and proximal His(F8)) are similar to those of other globin proteins. Two alternative conformations of the Arg84(E10) guanidium group were observed, suggesting that it participates in ligand binding to Cgb, as is the case for Arg(E10) of Aplysia Mb and Lys(E10) of Ngb. The structural diversities and similarities among globin proteins are discussed with relevance to molecular evolutionary relationships.
About this Structure
1V5H is a Single protein structure of sequence from Homo sapiens with as ligand. Full crystallographic information is available from OCA.
Reference
Structural basis of human cytoglobin for ligand binding., Sugimoto H, Makino M, Sawai H, Kawada N, Yoshizato K, Shiro Y, J Mol Biol. 2004 Jun 11;339(4):873-85. PMID:15165856
Page seeded by OCA on Thu Feb 21 15:31:41 2008
Categories: Homo sapiens | Single protein | Kawada, N. | Makino, M. | RSGI, RIKEN Structural Genomics/Proteomics Initiative. | Sawai, H. | Shiro, Y. | Sugimoto, H. | Yoshizato, K. | HEM | Globin | Heme | Ligand binding | Oxygen storage | Oxygen transport | Riken structural genomics/proteomics initiative | Rsgi | Structural genomics
