Vascular endothelium glycoprotein that plays an important role in the regulation of angiogenesis. Required for normal structure and integrity of adult vasculature. Important for endothelial cell shape changes in response to blood flow, which drive vascular remodeling and establishment of normal vascular morphology during angiogenesis. Homodimer; disulfide-linked. Detected in vascular tissue at 36-72 hours post-fertilization, where it localizes to endothelial cells. Viable, with survival to adult stages. Brain tissue shows widespread vascular malformations with localized widening of blood vessels. During embryogenesis, blood vessel connectivity between the dorsal aorta (DA), intersegmental vessels (ISVs) and posterior cardinal vein (PCV) appears normal at 72 hours post-fertilization (hpf). However, blood flow through ISVs is significantly reduced. Blood vessel pruning is increased, probably due to aberrant hemodynamics. Arterial ISVs have a slightly increased diameter, while venous ISVs have greatly reduced diameter. The DA and PCV are both significantly dilated. Endothelial cells in the DA show increased surface area and abnormal morphology in response to blood flow. In contrast, wild-type vessels respond to increased blood flow by an initial expansion phase, followed by vessel contraction. klf2a-mediated shear stress sensing is not affected. Has low similarity to mammalian endoglins and lacks the canonical ZP (zona pellucida) domain typically found in these proteins.