A secreted phosphoprotein, produced by many epithelial cell types, that is highly negatively charged and frequently associated with mineralization processes. It is found in plasma, urine, milk, and bile. Transformed cells express o. in elevated levels. SYN: bone sialoprotein 1.
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os·teo·pon·tin (os″te-o-ponґtin) an acidic calcium-binding phosphoprotein with a high affinity for hydroxyapatite, involved in bone mineralization and in dystrophic calcification.Medical dictionary. 2011.