Integrin-binding sialoprotein (IBSP)

Integrin-binding sialoprotein (IBSP), also known as bone sialoprotein, is a major non-collagenous structural protein of the bone matrix, constituting roughly 8–12% of all non-collagenous proteins in bone and dentin[1][2][3][4]. It is synthesized primarily by osteoblasts, osteocytes, osteoclasts, and hypertrophic chondrocytes, with notable expression in developing and remodeling bone tissue; the only non-bone source is the trophoblast[1][2][3][4]. IBSP is a highly acidic, sialic acid-rich protein that binds calcium and hydroxyapatite, supporting bone mineralization and extracellular matrix remodeling[1][2][3][4]. It contains an RGD sequence that enables cell attachment via integrin receptors (notably vitronectin receptor, αvβ3)[1][2][3]. IBSP is tightly regulated during bone development and is implicated in the genetic regulation of bone mineral density and susceptibility to diseases such as osteoporosis[1]. Aberrant expression has been linked to the metastatic potential of certain cancers, particularly breast cancer, as it mediates cellular interactions within the bone microenvironment[1][3]. It is widely used as a biomarker for osteogenesis and bone metastasis but is not currently targeted directly by approved drugs[1][3].

Other names

Bone sialoproteinBone sialoprotein IIBSPBSP-IISP-IIBNSPCell-binding sialoproteinBone sialoprotein 2

Modulation of cell adhesion by interaction with integrin receptors (notably αvβ3 integrin); Promotion of matrix mineralization and bone remodeling