Purity
>95%, by SDS-PAGE under reducing conditions and visualized by silver stain
Endotoxin Level
<0.10 EU per 1 μg of the protein by the LAL method.
Activity
Measured by its ability to inhibit the cell growth of Mv1Lu mink lung epithelial cells. Schiemann, B.J. et al. (2003) Mol. Biol. Cell. 14:3977. The ED 50 for this effect is 0.6‑2.4 µg/mL.
Optimal dilutions should be determined by each laboratory for each application.Source
Mouse myeloma cell line, NS0-derived Ala18-Ile302, with a C-terminal 10-His tag
Accession #
N-terminal Sequence
AnalysisAla18
Predicted Molecular Mass
34 kDa
SDS-PAGE
42 kDa, reducing conditions
942-SP |
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Formulation Lyophilized from a 0.2 μm filtered solution in PBS. | ||
Reconstitution Reconstitute at 100 μg/mL in sterile PBS. | ||
Shipping The product is shipped with polar packs. Upon receipt, store it immediately at the temperature recommended below. | ||
Stability & Storage: Use a manual defrost freezer and avoid repeated freeze-thaw cycles.
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Background: SPARC
SPARC, an acronym for “secreted protein, acidic and rich in cysteine”, is also known as osteonectin or BM-40 (1 - 5). It is the founding member of a family of secreted matricellular proteins with similar domain structure. The 302 amino acid (aa), 43 kDa protein contains a 17 aa signal sequence, an N-terminal acidic region that binds calcium, a follistatin domain containing Kazal-like sequences, and a C-terminal extracellular calcium (EC) binding domain with two EF-hand motifs (1 - 5). Crystal structure shows that residues implicated in cell binding, inhibition of cell spreading and disassembly of focal adhesions cluster on one face of SPARC, while a collagen binding epitope and an N-glycosylation site are opposite this face (6). SPARC is produced by fibroblasts, capillary endothelial cells, platelets and macrophages, especially in areas of tissue morphogenesis and remodeling (3, 7). SPARC shows context-specific effects, but generally inhibits adhesion, spreading and proliferation, and promotes collagen matrix formation (3 - 5). For endothelial cells, SPARC disrupts focal adhesions and binds and sequesters PDGF and VEGF (3 - 5). SPARC is abundantly expressed in bone, where it promotes osteoblast differentiation and inhibits adipogenesis (5, 8). SPARC is potentially cleaved by metalloproteinases, producing an angiogenic peptide that includes the copper-binding sequence KGHK (7). Paradoxically, SPARC is highly expressed in many tumor types, yet expression mainly decreases the likelihood of metastasis and confers sensitivity to chemotherapy and radiation (4, 9, 10). Stabilin-1, which is expressed on alternately activated macrophages, is the first SPARC receptor to be identified. It binds the SPARC EC domain and mediates endocytosis for degradation (11). Mature mouse SPARC shows 97%, 92%, 92%, 92% and 83% aa identity with rat, human, dog, cow and chick SPARC, respectively.
References:
Lankat-Buttgereit, B. et al. (1988) FEBS Lett. 236:352.
McVey, J.H. et al. (1988) J. Biol. Chem. 263:11111.
Sage, H. et al. (1989) J. Cell Biol. 109:341.
Framson, P.E. and E.H. Sage (2004) J. Cell. Biochem. 92:679.
Alford, A.I. and K.D. Hankenson (2006) Bone 38:749.
Hohenester, E. et al. (1997) EMBO J. 16:3778.
Sage, E.H. et al. (2003) J. Biol. Chem. 278:37849.
Delany, A.M. et al. (2003) Endocrinology 144:2588.
Koblinski, J.E. et al. (2005) Cancer Res. 65:7370.
Tai, I.T. et al. (2005) J. Clin. Invest. 115:1492.
Kzhyshkowska, J. et al. (2006) J. Immunol. 176:5825.
Long Name:
Secreted Protein Acidic and Rich in Cysteine
Entrez Gene IDs:
6678 (Human); 20692 (Mouse)
Alternate Names:
Basement-membrane protein 40; BM-40; ONcysteine-rich protein; Osteonectin; Secreted protein acidic and rich in cysteine; secreted protein, acidic, cysteine-rich (osteonectin); SPARC
