TIE1/TIE (tyrosine kinase with Ig and EGF homology domains 1) and TIE2/Tek define a new class of the receptor tyrosine kinase (RTK) subfamily with unique structural characteristics: two immunoglobulin like domains flanking three epidermal growth factor (EFG) like domains followed by three fibronectin type III like repeats in the extracellular region and a split tyrosine kinase domain in the cytoplasmic region.
Human TIE1 cDNA encodes a 1138aa residue precursor protein with a putative signal peptide, an extracellular domain, and a cytoplasmic domain.
TIE1 and TIE2, expressed primarily on endothelial and hematopoietic progenitor cells, play important roles in angiogenesis, vasculogenesis, and hematopoiesis.
In developing vascular endothelial cells, TIE1 and TIE2 are specifically expressed.
Two ligands that bind TIE have been identified, angiopoietin 1 and angiopoietin 2.
Based on gene targeting studies, the in vivo functions of TIE1 are related to endothelial cell differentiation.
TIE1 is a receptor that is implicated in vessel maturation and angiogenesis.