Rabbit Anti-Human TIE1 polyclonal antibody for IHC-P. TIE-1/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 TIE-1 cDNA encodes a 1138 amino acid residue precursor protein with a putative signal peptide, an extracellular domain, and a cytoplasmic domain. TIE-1 and TIE-2, expressed primarily on endothelial and hematopoietic progenitor cells, play important roles in angiogenesis, vasculogenesis, and hematopoiesis. In developing vascular endothelial cells, TIE-1 and TIE-2 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 TIE-1 are related to endothelial cell differentiation.