TPO stimulates the proliferation and maturation of megakaryocytes and promotes increased circulating levels of platelets in vivo. TPO signals through the c-mpl receptor and acts as an important regulator of circulating platelets

TPO is a ligand for the c-mpl proto-oncogene (Mpl-L), a megakaryocyte colony stimulating factor and primary regulatory factor for megakaryocytopoiesis and thrombopoiesis. TPO is a humoral glycoprotein that stimulates growth and maturation of megakaryocytes and megakaryocytic colonies from bone marrow cultures.

Thrombopoeitin is a primary regulatory factor for megakaryocytopoiesis and thrombopoiesis. The mature form of TPO is a highly conserved glycoprotein, showing homology among various mammals. It is produced by liver and kidney cells. TPO stimulates growth and maturation of megakaryocytes and megakaryocytic colonies from bone marrow cultures. TPO binds and activates an 68-78 kDa glycoprotein receptor belonging to the GH family of cytokine receptors, a family that includes receptors to growth hormone (GH), erythropoietin (EPO), and prolactin (PRL). Like GH and EPO, TPO may bind to its receptor at two distinct sites, initiating receptor dimerization and activation. Analysis of mRNA indicates also the existence of a novel truncated and potentially soluble form of TPO receptor. The viral oncogene v-mlp of the myeloproliferative leukemia virus (MPLV) contains the gene sequence for the entire cytoplasmic and transmembrane domains and a portion of the extracellular domain of c-mlp (TPO receptor).

Lyophilized from a 0.1 % TFA solution containing 250 μg bovine serum albumin

The biological activity is measured in a cell proliferation assay using MO7e cells.