4MZZ
Crystal structure of Bovine 3 Glu-Osteocalcin.
Summary for 4MZZ
| Entry DOI | 10.2210/pdb4mzz/pdb |
| Descriptor | Osteocalcin (2 entities in total) |
| Functional Keywords | structural genomics, protein structure initiative, nysgrc, psi-biology, new york structural genomics research consortium, structural protein |
| Biological source | Bos taurus (bovine,cow,domestic cattle,domestic cow) |
| Cellular location | Secreted: P02820 |
| Total number of polymer chains | 2 |
| Total formula weight | 7804.61 |
| Authors | Malashkevich, V.N.,Dowd, T.L.,Almo, S.C.,New York Structural Genomics Research Consortium (NYSGRC) (deposition date: 2013-09-30, release date: 2013-11-27, Last modification date: 2024-11-27) |
| Primary citation | Malashkevich, V.N.,Almo, S.C.,Dowd, T.L. X-ray crystal structure of bovine 3 Glu-osteocalcin. Biochemistry, 52:8387-8392, 2013 Cited by PubMed Abstract: The 3 Glu form of osteocalcin (3 Glu-OCN) is increased in serum during low vitamin K intake or oral anticoagulant use (warfarin). Previous reports using circular dichroism show it is less structured than 3 Gla Ca²⁺-osteocalcin and does not bind strongly to bone mineral. Recent studies have suggested a role for 3 Glu-OCN as a potential regulator of glucose metabolism. A G-protein-coupled receptor, GPRC6a, found in the pancreas and testes was identified as the putative osteocalcin receptor. The purpose of this study is to determine the high-resolution structure of bovine 3 Glu-OCN, using X-ray crystallography, to understand molecular interactions with mineral and the GPRC6a receptor. Diffraction quality crystals of thermally decarboxylated bovine osteocalcin were grown, and the crystal structure was determined to 1.88 Å resolution. The final refined structure contained residues 17-47 and, like 3 Gla Ca²⁺-OCN, consisted of three α-helices surrounding a hydrophobic core, a C23-C29 disulfide bond between two of the helices, and no bound Ca²⁺. Thus, the helical structure of 3 Glu-OCN is Ca²⁺-independent but similar to that of 3 Gla Ca²⁺-OCN. A reduced level of mineral binding could result from a lower number of Ca²⁺ coordinating ligands on 3 Glu-OCN. The structure suggests the GPRC6a receptor may respond to helical osteocalcin and will aid in providing molecular mechanistic insight into the role of 3 Glu-OCN in glucose homeostasis. PubMed: 24138653DOI: 10.1021/bi4010254 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (1.88 Å) |
Structure validation
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