Thrombopoietin (THPO) Active Protein

Megakaryocytopoiesis is the cellular development process that leads to platelet production. The main functional protein encoded by this gene is a humoral growth factor that is necessary for megakaryocyte proliferation and maturation, as well as for thrombopoiesis. This protein is the ligand for MLP/C_MPL, the product of myeloproliferative leukemia virus oncogene. Mutations in this gene are the cause of thrombocythemia 1. Alternative promoter usage and differential splicing result in multiple transcript variants differing in the 5' UTR and/or coding region. Multiple AUG codons upstream of the main open reading frame (ORF) have been identified, and these upstream AUGs inhibit translation of the main ORF at different extent. [provided by RefSeq, Feb 2014]

THPO: Lineage-specific cytokine affecting the proliferation and maturation of megakaryocytes from their committed progenitor cells. It acts at a late stage of megakaryocyte development. It may be the major physiological regulator of circulating platelets. Defects in THPO are the cause of thrombocythemia type 1 (THCYT1). A myeloproliferative disorder characterized by elevated platelet levels due to sustained proliferation of megakaryocytes, and frequently lead to thrombotic and haemorrhagic complications. Belongs to the EPO/TPO family. 3 isoforms of the human protein are produced by alternative splicing.

Protein type: Secreted; Cytokine; Cell cycle regulation; Secreted, signal peptide

Chromosomal Location of Human Ortholog: 3q27

Cellular Component: extracellular space

Molecular Function: growth factor activity; hormone activity; cytokine activity

Biological Process: cell proliferation; positive regulation of protein kinase B signaling cascade; platelet activation; multicellular organismal development; positive regulation of megakaryocyte differentiation; myeloid cell differentiation; positive regulation of protein amino acid phosphorylation; blood coagulation

Disease: Thrombocythemia 1