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-Structure paper
| タイトル | Structural insights into the vitamin K-dependent γ-carboxylation of osteocalcin. |
|---|---|
| ジャーナル・号・ページ | Cell Res, Vol. 35, Issue 10, Page 735-749, Year 2025 |
| 掲載日 | 2025年9月2日 |
著者 | Qing Cao / Jianjun Fan / Aaron Ammerman / Samjhana Awasthi / Zongtao Lin / Saimi Mierxiati / Huaping Chen / Jinbin Xu / Benjamin A Garcia / Bin Liu / Weikai Li / ![]() |
| PubMed 要旨 | The γ-carboxylation state of osteocalcin determines its essential functions in bone mineralization or systemic metabolism and serves as a prominent biomarker for bone health and vitamin K nutrition. ...The γ-carboxylation state of osteocalcin determines its essential functions in bone mineralization or systemic metabolism and serves as a prominent biomarker for bone health and vitamin K nutrition. This post-translational modification of glutamate residues is catalyzed by the membrane-embedded vitamin K-dependent γ-carboxylase (VKGC), which typically recognizes protein substrates through their tightly bound propeptide that triggers γ-carboxylation. However, the osteocalcin propeptide exhibits negligible affinity for VKGC. To understand the underlying molecular mechanism, we determined the cryo-electron microscopy structures of VKGC with osteocalcin carrying a native propeptide or a high-affinity variant at different carboxylation states. The structures reveal a large chamber in VKGC that maintains uncarboxylated and partially carboxylated osteocalcin in partially unfolded conformations, allowing their glutamate-rich region and C-terminal helices to engage with VKGC at multiple sites. Binding of this mature region together with the low-affinity propeptide effectively stimulates VKGC activity, similar to high-affinity propeptides that differ only in closely fitting interactions. However, the low-affinity propeptide renders osteocalcin prone to undercarboxylation at low vitamin K levels, thereby serving as a discernible biomarker. Overall, our studies reveal the unique interaction of osteocalcin with VKGC and provide a framework for designing therapeutic strategies targeting osteocalcin-related bone and metabolic disorders. |
リンク | Cell Res / PubMed:40890294 / PubMed Central |
| 手法 | EM (単粒子) |
| 解像度 | 3.13 - 3.56 Å |
| 構造データ | EMDB-48519, PDB-9mqb: EMDB-48520, PDB-9mqc: EMDB-48522, PDB-9mqe: |
| 化合物 | ![]() ChemComp-NAG: ![]() ChemComp-6PL: ![]() PDB-1avc: |
| 由来 |
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キーワード | TRANSFERASE / GGCX / VKGC / Vitamin K / VKCFD / Hemophilia B / Warfarin / Carboxylation / Blood Coagulation / Calcium homeostasis / Osteocalcin / MEMBRANE PROTEIN / calcium |
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