Angiopoietins are proteins with important roles invascular development and angiogenesis. All angiopoietins bind withsimilar affinity to an endothelial cell-specific tyrosine-proteinkinase receptor. The protein encoded by this gene is a secretedglycoprotein that activates the receptor by inducing its tyrosinephosphorylation. It plays a critical role in mediating reciprocalinteractions between the endothelium and surrounding matrix andmesenchyme. The protein also contributes to blood vessel maturationand stability, and may be involved in early development of theheart.