Osteocalcin, also known as bone gamma-carboxyglutamic acid-containing protein (BGLAP), is a noncollagenous proteinhormone found in bone and dentin, first identified as a calcium-binding protein in chick bone.
Osteocalcin is secreted solely by osteoblasts and thought to play a role in the body's metabolic regulation. In its carboxylated form it binds calcium directly and thus concentrates in bone, but genetic evidence has revealed that it does not play an important role in bone mineralization.
In its uncarboxylated form, osteocalcin acts as a hormone in the body, signalling in the pancreas, fat, muscle, testes, and brain.
As osteocalcin is produced by osteoblasts, it is often used as a marker for the bone formation process. It has been observed that higher serum osteocalcin levels are relatively well correlated with increases in bone mineral density during treatment with anabolic bone formation drugs for osteoporosis, such as teriparatide. In many studies, osteocalcin is used as a preliminary biomarker on the effectiveness of a given drug on bone formation. For instance, one study which aimed to study the effectiveness of a glycoprotein called lactoferrin on bone formation used osteocalcin as a measure of osteoblast activity.
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