Enables Notch binding activity. Involved in several processes, including blood vessel remodeling; circulatory system development; and regulation of Notch signaling pathway. Acts upstream of or within several processes, including Notch signaling pathway; angiogenesis; and negative regulation of blood vessel endothelial cell migration. Predicted to be integral component of plasma membrane. Predicted to be active in plasma membrane. Is expressed in several structures, including cardiovascular system; central nervous system; early conceptus; intestine; and sensory organ. Human ortholog(s) of this gene implicated in Adams-Oliver syndrome. Orthologous to human DLL4 (delta like canonical Notch ligand 4). [provided by Alliance of Genome Resources, Apr 2022]