Potent circulating inhibitor of angiogenesis. Signals through the type I activin receptor ACVRL1 but not other Alks. Signaling through SMAD1 in endothelial cells requires TGF-beta coreceptor endoglin/eng. Homodimer; disulfide-linked. A reversible disulfide bond can be formed between the two subunits in the homodimer; this has no effect on gdf2 activity. Morpholino knockdown of the protein causes slight decreases in both anterior-posterior and dorsal-ventral axes, while trunk and tail anatomy are otherwise normal. Vascular patterning is relatively normal, although defects are detected in maturation of the caudal vein: the caudal venous plexus fails to resolve and both dorsal and ventral veins continue to carry blood flow. Belongs to the TGF-beta family.