This gene encodes a peptide that functions as an endogenous ligand for the G-protein coupled apelin receptor. The encoded preproprotein is proteolytically processed into biologically active C-terminal peptide fragments. These peptide fragments activate different tissue specific signaling pathways that regulate diverse biological functions including fluid homeostasis, cardiovascular function and insulin secretion. This protein also functions as a coreceptor for the human immunodeficiency virus 1. APLN (Apelin) is a Protein Coding gene. Diseases associated with APLN include Syndrome Of Inappropriate Antidiuretic Hormone and Severe Pre-Eclampsia. Among its related pathways are Peptide ligand-binding receptors and Apelin signaling pathway. GO annotations related to this gene include receptor binding and G-protein coupled receptor binding.