Spp1

Function

Major non-collagenous bone protein that 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.

Post-translational modifications

Extensively phosphorylated by FAM20C in the extracellular medium at multiple sites within the S-x-E/pS motif (By similarity). The phosphorylated form inhibits hydroxyapatite crystallization (PubMed:23427088). Dephosphorylation via a mechanism involving ALPL/TNAP promotes hydroxyapatite crystallization (PubMed:23427088).

O-glycosylated.

Forms covalent cross-links mediated by transglutaminase TGM2, between a glutamine and the epsilon-amino group of a lysine residue, forming homopolymers and heteropolymers, increasing its collagen binding properties.

Sequence Similarities

Belongs to the osteopontin family.

Cellular localization

• Secreted

Alternative names

Eta-1, Op, Spp-1, Spp1, Osteopontin, 2AR, Bone sialoprotein 1, Calcium oxalate crystal growth inhibitor protein, Early T-lymphocyte activation 1 protein, Minopontin, Secreted phosphoprotein 1, SPP-1

Database links

swissprot:P10923 entrezGene:20750

Other research areas

• Immunology & Infectious Disease
• Neuroscience
• Oncology