Technical Data
Osteonectin, aa272-286 (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. (2).

Applications: Suitable for use in ELISA. Other applications not tested.

Recommended Dilution:
ELISA: 1:3000.
Optimal dilutions to be determined by the researcher.

Storage and Stability: Lyophilized powder may be stored at -20C. Reconstitute to nominal volume by adding sterile 25% glycerol and store at -20C. May be stored at 4C for short-term only. 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.
PabIgGNeat Serum
20ul-20CBlue IceHumanRabbit
Not determined
Synthetic human Osteonectin peptide (272-286) (CFGIKQKDIDKDLVI)
Neat Serum
Supplied as a lyophilized powder. No preservative added.
Synthetic human Osteonectin peptide (272-286), Recombinant human Osteonectin. No crossreactivity with human Osteopontin or human Bone Sialoprotein.
Intended for research use only. Not for use in human, therapeutic, or diagnostic applications.
General References:
1. Villarreal, X.C., et al., Biochemistry, 28, 6483 (1989). 2. Termine, J.D., et al., J. Biol. Chem., 256, 10403 (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, 14831 (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).