Bone sialoprotein (BSP) is a highly acidic phosphorylated glycoprotein found at high levels in mineralized tissues. Similar to other members of the SIBLING protein family, BSP is a multidomain, multifunctional adhesive protein with a flexible conformation and little secondary structure. BSP has been demonstrated to be involved in cell attachment and signaling, hydroxyapatite binding and nucleation, and collagen binding. It has also been proposed that the protein has angiogenic properties, promotes bone repair, enhances osteoclast formation, and mediates attachment of certain metastatic cancer cells to bone, among other putative functions. The flexible structure of BSP is believed critical in its ability to interact with multiple binding partners. Recent studies on the BSP-null mice have provided further evidence for a significant role for BSP in bone formation and remodeling.
Keywords: Bone sialoprotein, SIBLINGs, hydroxyapatite binding, mineral nucleation, angiogenesis, bone formation and remodeling, cell attachment and signaling, osteoblasts, osteoclasts, differentiation, cancer metastasis.