Sialoprotein

Sialoprotein is a term used for glycoproteins that contain sialic acid residues (sialylated glycoproteins). In biology, the label commonly refers to two well-characterized mineralized-tissue proteins: bone sialoprotein (BSP) and dentin sialoprotein (DSP). Both are secreted components of the extracellular matrix and are heavily glycosylated.

Bone sialoprotein is produced by osteoblasts and, during bone formation, binds hydroxyapatite and interacts with collagen I. It is thought to regulate mineral nucleation and may play a role in osteoblast adhesion and signaling, as well as osteoclast recruitment during remodeling. BSP is encoded by the IBSP gene. Expression rises during bone development and remodeling; altered BSP levels have been studied in metabolic bone diseases and certain cancers.

Dentin sialoprotein is produced by odontoblasts and is part of the dentin extracellular matrix. It is encoded by the DSPP gene, a precursor protein that is proteolytically cleaved to yield DSP and dentin phosphoprotein (DPP). DSP is implicated in dentin mineralization and dentin-dentinal tubule formation; DPP is highly acidic and phosphate-rich, supporting mineralization. DSPP mutations cause dentinogenesis imperfecta type II and related conditions.

In broader terms, sialoproteins contribute to cell adhesion, signaling, and molecular recognition via their sialic acid residues. The term is often used in dental and bone biology to refer specifically to BSP and DSP.