Osteocalcin
experimentalAlso known as: Bone Gla protein, Gamma-carboxyglutamic acid-containing protein, BGLAP, P02818
**Mechanism of Action** Osteocalcin (bone Gla protein, BGLAP) is a small, vitamin K-dependent protein secreted primarily by osteoblasts. Its mechanism involves post-translational gamma-carboxylation of glutamic acid residues, enabling calcium-binding and incorporation into the bone extracellular matrix. The carboxylated form constitutes 1–2% of total bone protein and contributes to hydroxyapatite crystal maturation and bone mineralization. Additionally, uncarboxylated osteocalcin acts as a hormone, influencing glucose metabolism, insulin sensitivity, and male fertility via binding to GPRC6A receptors in pancreatic beta cells, adipose tissue, and Leydig cells. **Key Research Findings** Preclinical studies demonstrate that osteocalcin knockout mice exhibit increased bone mass but impaired glucose tolerance and reduced insulin secretion, suggesting a dual role in skeletal and metabolic regulation. Human observational studies link serum osteocalcin levels to bone turnover markers, with elevated levels in high-turnover states (e.g., osteoporosis, hyperparathyroidism) and reduced levels in aging or diabetes. Experimental research also explores its role in vascular calcification and exercise-induced bone adaptation, though findings remain correlational. **Clinical Relevance** Osteocalcin is a validated biomarker for bone formation in clinical settings, used to monitor osteoporosis treatment (e.g., bisphosphonates, teriparatide) and metabolic bone diseases. Its endocrine functions have sparked interest in potential therapeutic applications for type 2 diabetes and hypogonadism, but these remain experimental. No osteocalcin-based therapies are approved for clinical use. For research purposes only — not medical advice.
Key data
MRALTLLALLALAALCIAGQAGAKPSGAESSKGAAFVSKQEGSEVVKRPRRYLYQWLGAPVPYPDPLEPRREVCELNPDCDELADHIGFQEAYRRFYGPVMechanism of action
The carboxylated form is one of the main organic components of the bone matrix, which constitutes 1-2% of the total bone protein (PubMed:3019668, PubMed:6967872). Acts as a negative regulator of bone formation and is required to limit bone formation without impairing bone resorption or mineralization (By similarity). Binds strongly to apatite and calcium upon gamma-carboxylation; this modification is essential for bone metabolism (PubMed:6967872, PubMed:39880952)
Research & studies
Decarboxylated osteocalcin promotes insulin secretion and pancreatic islet β-cell proliferation.; It reduces visceral fat accumulation and liver fat storage.; Osteocalcin levels inversely correlate with fasting glucose, body fat, and BMI.; It influences testosterone production, GLP-1 synthesis, muscle-bone crosstalk, and cognitive function.
Osteocalcin haploinsufficiency in embryos of Osteocalcin-deficient mothers impairs insulin secretion, liver gluconeogenesis, and testes steroidogenesis in adult offspring.; Osteocalcin deficiency inhibits cell proliferation in developing pancreatic islets and testes.; Osteocalcin disrupts gene expression programs in the pancreas, liver, testes, and brain.; Maternal and embryonic osteocalcin synergize to establish and maintain organismal homeostasis in newborn and adult offspring.
Osteocalcin is a bone-derived hormone with broad physiological effects in rodents and primates.; It influences energy metabolism, steroidogenesis, neurotransmitter biosynthesis, male fertility, electrolyte homeostasis, cognition, stress response, and exercise capacity.; Osteocalcin acts by binding to one of three receptors.; The review proposes a common theme between osteocalcin's functions and bone's structural functions.
Frequently asked questions
What is Osteocalcin?
**Mechanism of Action** Osteocalcin (bone Gla protein, BGLAP) is a small, vitamin K-dependent protein secreted primarily by osteoblasts. Its mechanism involves post-translational gamma-carboxylation of glutamic acid residues, enabling calcium-binding and incorporation into the bone extracellular matrix. The carboxylate
How does Osteocalcin work?
The carboxylated form is one of the main organic components of the bone matrix, which constitutes 1-2% of the total bone protein (PubMed:3019668, PubMed:6967872). Acts as a negative regulator of bone formation and is required to limit bone formation without impairing bone resorption or mineralization (By similarity). Binds strongly to apatite and calcium upon gamma-carboxylation; this modification
What is the research status of Osteocalcin?
Osteocalcin is currently classified as experimental, with 20,513 research references on record. This is for research purposes only and is not medical advice.
What is the molecular weight of Osteocalcin?
Osteocalcin has a molecular weight of approximately 10963 g/mol.
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