Angiopoietins are proteins with important roles in vascular development and angiogenesis. All angiopoietins bind with similar affinity to an endothelial cell-specific tyrosine-protein kinase receptor. The mechanism by which they contribute to angiogenesis is thought to involve regulation of endothelial cell interactions with supporting perivascular cells.
Angiopoietin 3 (ANG3), also called ANG4, might represent counterparts in mouse and human. Based on chromosomal analysis, mouse ANG3 is thought to be an ortholog of human ANG4. Human ANG4 acts as an agonist that binds and activates Tie2, whereas mouse ANG3 is likely to be a Tie2 antagonist, exerting agonist or antagonist activities depending on the cell context. Mouse ANG3 is expressed in various mouse tissues. Mouse angiopoietin 3 is a secreted glycoprotein and member of the angiopoietin family. It has an N terminal coiled-coil domain and a Cbterminal fibrinogen like domain. The coiled coil domains mediate ligand homo oligomerization and the fibrinogen like domains mediate ligand activity. Recombinant mouse angiopoietin 3 has a calculated molecular mass of 58 kDa. Due to glycosylation, the recombinant protein (containing 3 peptides) has an apparent molecular mass of 85-90 kDa in SDS-PAGE under reducing conditions. Mouse angiopoietin 3 shares 47%, 46%, and 54% sequence identity with mouse ANG1, mouse ANG2, and human ANG4, respectively.