• Purity

  >90%, by SDS-PAGE under reducing conditions and visualized by silver stain.

• Endotoxin Level

  <1.0 EU per 1 μg of the protein by the LAL method.  

• Activity

  Measured by the ability of the immobilized protein to support the adhesion of SVEC4‑10 mouse vascular endothelial cells. Recombinant Human Thrombospondin‑4 (rhThrombospondin-4) is coated to 96 well plates at 10 µg/mL (100 µL/well) overnight then reduced with 20 mM DTT for 30 minutes. When 2 x 10    ⁴ cells/well are added to rhThrombospondin‑4 coated plates, ≥50% will adhere after one hour at 37 °C.    
     Optimal dilutions should be determined by each laboratory for each application.  

• Source

  Chinese Hamster Ovary cell line, CHO-derived Ala22-Asn961, with a C-terminal 10-His tag

• Accession #

• N-terminal Sequence    
  Analysis

  Ala22

• Predicted Molecular Mass

  105 kDa

• SDS-PAGE

  145 kDa, reducing conditions

Background: Thrombospondin-4

Thrombospondin-4 (TSP-4) is an approximately 140 kDa matricellular protein that is secreted as a disulfide-linked pentamer. Within the Thrombospondin family, TSP-3 and TSP-5/COMP are also pentameric, while TSP-1 and TSP-2 are trimeric. TSP-4 regulates cell-cell and cell matrix interactions and plays a role in cardiovascular physiology and neuronal development (1, 2). Mature human TSP-4 consists of an N-terminal heparin-binding domain, a coiled coil motif, four EGF-like repeats, seven TSP type-3 repeats (one with an RGD motif), and a TSP C-terminal domain (2). Human TSP-4 shares 93% amino acid sequence identity with mouse and rat TSP-4. TSP-4 binds a variety of matrix proteins including Collagens I, II, III, V, Laminin-1, Fibronectin, and Matrilin-2 (3). Interactions of TSP-4 with non-collagenous proteins are independent of divalent cations, whereas interactions with collagenous proteins are enhanced in the presence of zinc (3). TSP-4 binds to cell surface Integrins containing the alpha M, beta 2, or beta 3 chains (4, 5). It is expressed in skeletal muscle and tendon as well as by vascular smooth muscle and endothelial cells (6‑8). It is up‑regulated in cardiomyocytes during pressure overload and is required for mediating the responsive increase in cardiac contractility (9). In humans, a polymorphism of TSP-4 (A387P) is associated with myocardial infarction (10). TSP-4 contributes to the development of inflammation and atherosclerosis by promoting macrophage and neutrophil adhesion to the vasculature (4, 5). In the nervous system, TSP-4 is expressed by astrocytes and neurons and is enriched at neuromuscular junctions and synapse-rich layers of the brain and retina (8, 11, 12). It promotes neuronal adhesion, neurite outgrowth, and excitatory synaptogenesis (8, 12, 13). TSP-4 is  
up‑regulated in the spinal cord following peripheral nerve injury where it contributes to presynaptic hypersensitivity and hyperalgesia (11). It is also up‑regulated in muscle following denervation (8). TSP-4 is additionally secreted by tumor-associated fibroblasts in gastric adenocarcinoma, particularly in regions of tumor cell invasion (14).

• References:

1. Murphy-Ullrich, J.E. and R.V. Iozzo (2012) Matrix Biol. 31:152.

2. Lawler, J. et al. (1995) J. Biol. Chem. 270:2809.

3. Narouz-Ott, L. et al. (2000) J. Biol. Chem. 275:37110.

4. Pluskota, E. et al. (2005) Blood 106:3970.

5. Frolova, E.G. et al. (2010) Circ. Res. 107:1313.

6. Sodersten, F. et al. (2007) Connect. Tiss. Res. 48:254.

7. Stenina, O.I. et al. (2003) Circulation 108:1514.

8. Arber, S. and P. Caroni (1995) J. Cell Biol. 131:1083.

9. Cingolani, O.H. et al. (2011) Circ. Res. 109:1410.

10. Stenina, O.I. et al. (2007) Arterioscler. Thromb. Vasc. Biol. 27:1886.

11. Kim, D.-S. et al. (2012) J. Neurosci. 32:8977.

12. Dunkle, E.T. et al. (2007) Exp. Eye Res. 84:707.

13. Eroglu, C. et al. (2009) Cell 139:380.

14. Forster, S. et al. (2011) Mod. Pathol. 24:1390.

• Entrez Gene IDs:

  7060 (Human); 21828 (Mouse)

• Alternate Names:

  THBS4; thrombospondin 4; Thrombospondin4; Thrombospondin-4; TSP4; TSP-4