Apelin Receptors

The Apelin (APJ) receptor is a G-protein-coupled receptor for which Apelin-36, apelin-13 and [Pyr1]-apelin-13 are the predominant endogenous ligands. Elabela (ELA; also known as Toddler) has been proposed as another endogenous ligand for this receptor. The APJ receptor mediates cardiovascular function, fluid homeostasis and adipocyte endocrine secretion.

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Gene Data

Apelin Receptor Agonists

Cat. No. Product Name / Activity
2420 [Pyr1]-Apelin-13
Potent peptide apelin agonist
3007 Apelin-17 (human, bovine)
Endogenous apelin agonist
2426 Apelin-36 (human)
Endogenous apelin agonist
5966 ML 233
Non-peptide apelin agonist

Apelin Receptor Antagonists

Cat. No. Product Name / Activity
4748 ML 221
Apelin antagonist
5992 MM 54
Potent apelin antagonist

The apelin receptor comprises 380 amino acids and exhibits homology with the angiotensin II type 1 receptor (AT1), although it does not bind angiotensin. No apelin receptor subtypes have been discovered to date. In humans, APJ receptors are expressed in endothelial cells and cardiomyocytes, and throughout the brain and spinal cord. In the periphery the highest expression levels are seen in the spleen and placenta, while lower levels of expression are seen in other tissues. APJ receptors are also present in neonatal tissues.

Apelin is initially expressed as the 77-amino acid peptide pre-pro-apelin. Following secretion, the peptide is cleaved to produce three main apelin fragments: apelin 36, apelin-17 and apelin-16. Apelin is thought to signal primarily through Gαi, although there is evidence that the receptor may also couple to Gαq. Elabela is a 54-amino acid peptide that is cleaved to produce a 32-amino acid secreted peptide. ELA peptides display some bias toward the G protein pathway versus the β-arrestin signaling pathway, although both Apelin and ELA probably have different signaling profiles in different tissues and organs.

Apelin has a significant role in the cardiovascular system, causing vasodilation and having a positive inotropic effect. It regulates fluid homeostasis via the hypothalamic-pituitary-adrenal axis and modulates cardiovascular function via the forebrain and brain stem. Increased apelin expression is associated with certain cancers, inducing endothelial cell migration and proliferation, and promoting neoangiogenesis. In addition, apelin inhibits insulin secretion, decreases glucose levels, regulates gut glucose absorption, and has a role in the pathogenesis of diabetes-related complications.

ELA is important in development, particularly of the cardiovascular system, and promotes self-renewal of human embryonic stem cells.

External sources of pharmacological information for Apelin Receptors :

Apelin Receptor Gene Data

Species Gene Symbol Gene Accession No. Protein Accession No.
Human APLNR NM_005161 P35414
Mouse Aplnr NM_011784 Q9WV08
Rat Aplnr NM_031349 Q9JHG3