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osteopontin; bone sialoprotein 1; urinary stone protein; secreted phosphoprotein 1; nephropontin; uropontin (SPP1, BNSP, OPN)
Function:
1) multifunctional protein:
2) principal phosphorylated glycoprotein of bone
a) binds tightly to hydroxyapatite
b) appears to form an integral part of the mineralized matrix
c) probably important to cell-matrix interaction
3) acts as a cytokine involved in enhancing production of interferon-gamma & interleukin-12 & reducing production of interleukin-10 & is essential in the pathway that leads to cellular immunity (putative)
4) ligand of CD44
5) ligand of integrin alpha-V/beta-3
6) extensively phosphorylated on clustered serine residues
- phosphorylation sites are present in the extracellular medium
Structure:
- N-glycosylated & O-glycosylated
- belongs to the osteopontin family
Compartment:
- constituent of amorphous material within normal elastic fibers in human skin & aorta
Alternative splicing: named isoforms=4
Expression:
1) expressed in brain by:
a) microvascular endothelial cells
b) microglia
c) reactive astrocytes
d) neurons
2) expression induced by hypoxia
Pathology:
1) abundant in plaques of multiple sclerosis
2) urinary stone protein
Interactions
molecular events
Related
CD44; phagocytic glycoprotein I; PGP-1; HUTCH-I; extracellular matrix receptor-III; ECMR-III; GP90 lymphocyte homing/adhesion receptor; Hermes antigen; hyaluronate receptor; heparan sulfate proteoglycan; epican; CDw44 (LHR, MDU2, MDU3, MIC4)
General
glycoprotein
phosphoprotein
secreted protein
Properties
SIZE: entity length = 314 aa
MW = 35 kD
COMPARTMENT: extracellular compartment
MOTIF: signal sequence {1-16}
Ser phosphorylation site {S24}
Ser phosphorylation site {S26}
Ser phosphorylation site {S27}
Ser phosphorylation site {S62}
Ser phosphorylation site {S63}
Thr phosphorylation site {T66}
Ser phosphorylation site {S76}
N-glycosylation site {N79}
Ser phosphorylation site {S81}
Ser phosphorylation site {S99}
Ser phosphorylation site {S102}
Ser phosphorylation site {S105}
N-glycosylation site {N106}
Ser phosphorylation site {S108}
Ser phosphorylation site {S117}
Ser phosphorylation site {S120}
Ser phosphorylation site {S123}
Ser phosphorylation site {S126}
Ser phosphorylation site {S129}
Thr glycosylation site {T134}
Thr glycosylation site {T138}
Thr glycosylation site {T143}
Thr glycosylation site {T147}
Thr glycosylation site {T152}
Cell attachment site {159-161}
Thr phosphorylation site {T185}
Ser phosphorylation site {S191}
Ser phosphorylation site {S195}
Ser phosphorylation site {S215}
Ser phosphorylation site {S219}
Ser phosphorylation site {S224}
Ser phosphorylation site {S228}
Ser phosphorylation site {S234}
Ser phosphorylation site {S254}
Ser phosphorylation site {S263}
Ser phosphorylation site {S267}
Ser phosphorylation site {S275}
Ser phosphorylation site {S280}
Ser phosphorylation site {S303}
Ser phosphorylation site {S308}
Ser phosphorylation site {S310}
Database Correlations
OMIM 166490
UniProt P10451
Pfam PF00865
Entrez Gene 6696
Kegg hsa:6696
References
- UniProt :accession P10451
- Atlas of Genetics & Cytogenetics in Oncology & Haematology
http://atlasgeneticsoncology.org/genes/SPP1ID42379ch4q22.html
- Wikipedia; Note: osteopontin entry
http://en.wikipedia.org/wiki/osteopontin
- Journal Watch 22(2):16, 2002
Chabas D et al
The influence of the proinflammatory cytokine, osteopontin,
on autoimmune demyelinating disease.
Science 294:1731, 2001
PMID: 11721059
- OMIM :accession 166490
Component-of
molecular complex