APLN

Peptide hormone that functions as endogenous ligand for the G protein-coupled apelin receptor (APLNR/APJ), that plays a role in cadiovascular homeostasis. Functions as a balanced agonist activating both G(i) protein pathway and beta-arrestin pathway of APLNR. Downstream G proteins activation, apelin can inhibit cAMP production and activate key intracellular effectors such as ERKs. On the other hand, APLNR activation induces beta-arrestin recruitment to the membrane leading to desensitization and internalization of the receptor. Apelin blunts cardiac hypertrophic induction from APLNR on response to pathological stimuli, but also induces myocardial hypertrophy under normal conditions. Apelin-36 dissociates more hardly than (pyroglu)apelin-13 from APLNR (By similarity). Involved in the regulation of cardiac precursor cell movements during gastrulation and heart morphogenesis (By similarity). Has an inhibitory effect on cytokine production in response to T-cell receptor/CD3 cross-linking; the oral intake of apelin in the colostrum and the milk might therefore modulate immune responses in neonates (By similarity). Plays a role in early coronary blood vessels formation (By similarity). Mediates myocardial contractility in an ERK1/2-dependent manner (By similarity). May also have a role in the central control of body fluid homeostasis by influencing vasopressin release and drinking behavior (By similarity)..

Function from UniProtKB (Q9ULZ1), read 2026-09-23. CC BY 4.0.