Thrombospondin1 (TSP1) is a 150180kD calciumsensitive protein that is secreted as a disulfidelinked homotrimer. Within the Thrombospondin family, TSP2 is also homotrimeric, while TSP3, 4, and 5/COMP are pentameric. TSP1 regulates a wide range of cellular functions including their interactions with other cells and with the extracellular matrix (ECM). TSP1 contains an Nterminal Laminin Glike globular domain, an extended central region with one vWFC domain, 3 TSP type 1 repeats, 3 EGFlike domains, and 8 TSP type3 repeats, and a globular Cterminal lectin domain. Distinct regions of TSP1 have been associated with binding to particular ECM or cellular molecules (1, 2). Mature mouse TSP1 shares 95% and 99% amino acid sequence identity with human and rat TSP1, respectively. TSP1 counteracts the angiogenic, hypotensive, and antithrombotic effects of nitric oxide (NO) (3). It binds and neutralizes VEGF, blocks VEGF R2 signaling on vascular endothelial cells (EC), and destabilizes adhesive contacts between EC (46). TSP1s actions on vascular smooth muscle cells support arterial tone and blood pressure in the presence of vasodilatory stimulation (7). It is released from activated platelets and enhances platelet aggregation and adhesion (8). TSP1 also plays an important role in wound repair and tissue fibrosis by binding latent TGFbeta and inducing release of the active cytokine from the latency associated peptide (LAP) (9, 10). TSP1 dampens adaptive immune responses by inducing the differentiation of regulatory T cells and inhibiting TCR signaling (11, 12). In the nervous system, it promotes excitatory synapse formation (13, 14) and supports the integration of neural progenitor cells into the olfactory bulb (15). In addition, TSP1 is released by apoptotic cells and promotes macrophagemediated debris clearance (16). Source: Recombinant protein corresponding to aa22-326 from rat Thrombopoietin, NS0-derived. Molecular Weight: ~130-155kD Storage and Stability: Lyophilized and reconstituted products are stable for 6 months after receipt at -20C. Reconstitute with sterile PBS. Aliquot to avoid repeated freezing and thawing. Store 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.
