Thrombopoietin, Recombinant, Rat, aa22-326 (MGDF, MK-CSF, THPO, Tpo)

Thrombopoietin (Tpo), is a key regulator of megakaryocytopoiesis and thrombopoiesis. It is principally produced in the liver and is bound and internalized by the receptor Tpo R/c­mpl. Defects in the Tpo­Tpo R signaling pathway are associated with a variety of platelet disorders (1­3). Mature rat Tpo shares 68% and 81% aa sequence homology with human and mouse Tpo, respectively (4). It is an 80­85kD protein that consists of an N­terminal domain with homology to Erythropoietin (Epo) and a C­terminal domain that contains multiple N­linked and O­linked glycosylation sites. Tpo promotes the differentiation, proliferation, and maturation of megakaryocytes (MK) and their progenitors (5­7). Several other cytokines can also promote these functions but only in cooperation with Tpo (8, 9). Notably, IL­3 independently induces MK development, although its effects are restricted to early in the MK lineage (8, 9). Tpo additionally promotes platelet production, aggregation, ECM adhesion, and activation (10­13). These actions, in combination with direct effects on cardiomyocytes, can aid in the recovery of heart function following myocardial infarction (14). Tpo is cleaved by platelet­derived thrombin following Arg191 within the C­terminal domain and subsequently at other sites upon extended digestion (15). The C­terminal domain is not required for binding to Tpo R or inducing MK growth and differentiation (6). Aside from its hematopoietic effects, Tpo is expressed in the brain where it promotes the apoptosis of hypoxia­sensitized neurons and inhibits neuronal differentiation by blocking NGF­induced signaling (16, 17). Source: Recombinant protein corresponding to aa22-326 from rat Thrombopoietin, NS0-derived. Molecular Weight: ~50-66kD, Endotoxin: <0.10EU/1ug (LAL method), Storage and Stability: Lyophilized powder may be stored at -20°C. Stable for 12 months at -20°C. Reconstitute with sterile ddH2O or PBS. Aliquot to avoid repeated freezing and thawing. Store at -20°C. Reconstituted product is stable for 12 months at -20°C. 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.