Binds tightly to hydroxyapatite. Appears to form an integral part of the mineralized matrix. Probably important to cell-matrix interaction. Acts as a cytokine involved in enhancing production of interferon-gamma and interleukin-12 and reducing production of interleukin-10 and is essential in the pathway that leads to type I immunity.
Bone. Found in plasma.
Belongs to the osteopontin family.
Extensively phosphorylated on clustered serine residues. N- and O-glycosylated. Phosphorylation sites are present in the extracelllular medium.