Osteocalcin: Bone as an Endocrine Organ

Bone was long treated as a passive structural tissue, but osteoclast-mediated resorption releases the osteoblast-derived protein osteocalcin into circulation, where an acid-driven decarboxylation step activates it as a genuine hormone. This simulator renders a 3D bone segment being resorbed by osteoclasts, tracks matrix-bound osteocalcin as it is released and decarboxylated inside the acidic lacuna, and follows the active undercarboxylated form as it circulates to a pancreatic islet, binds GPRC6A receptors on beta cells, and drives insulin secretion — with an optional feedback arm where that insulin signals back to osteoblasts, closing a real bone-pancreas endocrine loop.