Osteopontin

Osteopontin is a secreted glycoprotein that functions as a ligand to alphavbeta3 integrin and possibly other receptors. It binds tightly to hydroxyapatite and can act as a structural component of the extracellular mineralized matrix. Osteopontin is initially secreted as a 298 amino acid protein, which is subject to multiple post-translational modifications including glycosylation, phosphorylation, and specific proteolytic cleavages into various smaller molecular weight fragments. Osteopontin is expressed in a wide range of cells and tissues including osteoblasts, various tumor cell lines, and extraosseous cells in the inner ear, brain, kidney, deciduum, placenta and odontoblasts. In addition to its involvement in mineralized matrix formation, Osteopontin can also function as a cytokine that stimulates the release of IFNγ and IL-12, while inhibiting the production of IL-10. Recombinant human Osteopontin is a 298 amino acid protein, which, due to glycosylation, migrates at an apparent molecular weight of 60-65 kDa by SDS-PAGE analysis under reducing conditions. Recombinant human Osteopontin has a calculated, theoretical molecular weight of 33.7 kDa.