Predicted to enable apelin receptor binding activity and hormone activity. Involved in circulatory system development and positive regulation of blood vessel endothelial cell proliferation involved in sprouting angiogenesis. Acts upstream of or within SMAD protein signal transduction. Located in extracellular space. Is expressed in several structures, including embryo ectoderm; embryo endoderm; gut; heart; and metanephros. Used to study pre-eclampsia. Orthologous to human APELA (apelin receptor early endogenous ligand). [provided by Alliance of Genome Resources, Apr 2022]