Recombinant Mouse Angiopoietin-3 Protein

Mouse angiopoietin-3 (ANG-3) (1), is a secreted glycoprotein belonging to the angiopoietin family. It has the characteristic structural motifs of angiopoietins including the coiled-coiled domain near the amino-terminus and a fibrinogen-like domain at the C-terminus. Mouse ANG-3 cDNA encodes a 509 amino acid (aa) precursor protein with a 21 aa signal peptide. It shares 47%, 46% and 54% aa sequence identity with mouse ANG-1, mouse ANG-2 and human ANG-4, respectively. Although the sequence homology is much higher between the human and mouse counterparts for ANG-1 (97%) and ANG-2 (85%), mouse ANG-3 is believed to be an ortholog of human ANG-4 based on chromosomal localization studies (1, 2). Human ANG-4 is highly expressed in lung and in cultured human umbilical vein endothelial cells (HUVECs). In contrast, mouse ANG-3 is expressed in multiple mouse tissues. Human ANG-4 is an agonist that can bind and activate Tie-2, a receptor tyrosine kinase with immunoglobulin and epidermal growth factor homology domains expressed primarily on endothelial cells and early hematopoietic cells (2, 3). Mouse ANG-3 has been reported to be a Tie-2 antagonist. It is likely that mouse ANG-3, like ANG-2, may exert agonist or antagonist activities depending on the cell context (1, 3, 4).