Technical Data
Osteonectin (SPARC, Secreted Protein, Acidic, Cysteine-rich, ON, OSN)
Osteonectin is an acidic, noncollagenous glycoprotein (Mr=29,000) originally isolated from fetal and adult bovine bone matrix (1-5). In vitro bovine bone osteonectin binds type I collagen, calcium (Kd=3x10(-7)M) and hydroxyapatite (Kd=8x10(-8)M) and has been shown to be a potent inhibitor of hydroxyapatite seeded crystal growth (6). In this context it has been suggested that osteonectin may play an important role in the regulation of bone metabolism by binding hydroxyapatite to collagen. Recently, proteins homologous to osteonectin nave been identified in a number of cell types, most of which are associated with extracellular matrix production (7). The amino acid sequence (from cDNA sequences) of one of these proteins, human placental SPARC, is identical to human bone osteonectin. Osteonectin has also been identified as an alpha granule component of human platelets and is secreted during platelet activation. A small portion of the secreted osteonectin is expressed on the platelet cell surface in an activation-dependent manner (8). Purified platelet osteonectin is a single chain molecule which exhibits a slightly larger apparent molcular weight than that of osteonectin derived from bone (8). The NH2-terminal sequences of platelet and bone-derived osteonectin are identical, but the two proteins differ with regard to the extent of glycosylation (8-10). Human platelet osteonectin is isolated from thrombin-activated platelets as described by Kelm, et al. (8). Bovine bone osteonection is isolated from demineralized bone by the method of Romberg, et al. (3).

Suitable for use in ELISA and Immunohistochemistry. Other applications have not been tested.

Recommended Dilution:
ELISA: 1:5000
Immunohistochemistry (Paraffin): 1:1000
Optimal dilutions to be determined by the researcher.

Storage and Stability:
Lyophilized powder may be stored at -20C. Stable for 12 months at -20C. Reconstitute with sterile ddH2O. Aliquot to avoid repeated freezing and thawing. Store at -20C. Reconstituted product is stable for 12 months at -20C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.
100ul-20CBlue IceHumanRabbit
Not Determined
Human Osteonectin
Supplied as a lyophilized powder. Reconstitute with 100ul sterile ddH2O.
Recognizes human Osteonectin (ON).
Intended for research use only. Not for use in human, therapeutic, or diagnostic applications.
1. Villarreal, X.C., et al., Biochemistry 28: 6483 (1989). 2. Termine, J.D., et al., J. Biol. Chem. 256: 10,403 (1981). 3. Romberg, R.W., et al., J. Biol. Chem. 260: 2728 (1985). 4. Tracy, R.P., et al., Int. J. Biochem. 29: 653 (1988). 5. Stenner, D.D., et al., Proc. Natl. Acad. Sci. USA, 83: 6892 (1986). 6. Romberg, R.W., et al., Biochemistry 25: 1176 (1986). 7. Sage, E.H. and Bornstein, P.J., J. Biol. Chem. 266: 14,831 (1991). 8. Kelm, R.J. and Mann, K.G., J. Bone Min. Res. 4: 5245 (1989). 9. Kelm, R.J. and Mann, K.G., Blood 75: 1105 (1990). 10. Kelm, R.J., et al., Blood 80: 3112 (1992). 11. Fisher, L.W., et al., J. Biol. Chem. 262: 9702 (1987).