| Thrombospondin4 (TSP-4) is an ~140kD matricellular protein that is secreted as a disulfidelinked pentamer. Within the Thrombospondin family, TSP3 and TSP5/COMP are also pentameric, while TSP1 and TSP2 are trimeric. TSP4 regulates cellcell and cell matrix interactions and plays a role in cardiovascular physiology and neuronal development (1, 2). Mature mouse TSP-4 consists of an Nterminal heparinbinding domain, a coiled coil motif, four EGFlike repeats, seven TSP type3 repeats (one with an RGD motif), and a TSP Cterminal domain (2, 3). Mouse TSP-4 shares 93% and 97% amino acid sequence identity with human and rat TSP-4, respectively. TSP-4 binds a variety of matrix proteins including Collagens I, II, III, V, Laminin1, Fibronectin, and Matrilin2 (4). Interactions of TSP-4 with noncollagenous proteins are independent of divalent cations, whereas interactions with collagenous proteins are enhanced in the presence of zinc (4). TSP-4 binds to cell surface Integrins containing the alphaM, beta2, or beta3 chains (5, 6). It is expressed in skeletal muscle and tendon as well as by vascular smooth muscle and endothelial cells (79). It is upregulated in cardiomyocytes during pressure overload and is required for mediating the responsive increase in cardiac contractility (10). In humans, a polymorphism of TSP4 (A387P) is associated with myocardial infarction (11). TSP-4 contributes to the development of inflammation and atherosclerosis by promoting macrophage and neutrophil adhesion to the vasculature (5, 6). In the nervous system, TSP-4 is expressed by astrocytes and neurons and is enriched at neuromuscular junctions and synapserich layers of the brain and retina (9, 12, 13). It promotes neuronal adhesion, neurite outgrowth, and excitatory synaptogenesis (9, 13, 14). TSP-4 is upregulated in the spinal cord following peripheral nerve injury where it contributes to presynaptic hypersensitivity and hyperalgesia (12). It is also upregulated in muscle following denervation (9). TSP-4 is additionally secreted by tumorassociated fibroblasts in gastric adenocarcinoma, particularly in regions of tumor cell invasion (15). Description: Recombinant protein corresponding to aa27-963, Gln27-Asn963, from mouse Thrombospondin-4, fused to 6xHis-Tag at C-terminal, expressed in CHO cells. Molecular Weight: ~120-245kD Endotoxin: <0.1EU/1ug (LAL) Biological Activity: Measured by the ability of the immobilized protein to support the adhesion of SVEC4-10 mouse vascular endothelial cells. The ED50 for this effect is 0.1-0.5ug/ml. Storage and Stability: Lyophilized powder may be stored at -20C. Stable for 12 months at -20C. Reconstitute in sterile PBS. 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. |
