Enables apelin receptor binding activity and identical protein binding activity. Involved in several processes, including apelin receptor signaling pathway; positive regulation of peptide hormone secretion; and regulation of blood circulation. Located in extracellular space and perinuclear region of cytoplasm. Used to study congestive heart failure. Biomarker of colitis; congestive heart failure; hypertension; and obesity. Orthologous to human APLN (apelin). [provided by Alliance of Genome Resources, Apr 2022]