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Peptide hormone

Apelin

Apelin is an endogenous peptide hormone processed from a 77-amino-acid precursor into active fragments such as apelin-13 and apelin-36. It is one of two natural ligands of the G-protein-coupled APJ (APLNR) receptor and is studied for roles in cardiovascular function, fluid homeostasis and adipose signaling. This page is educational and not medical advice.

By The Peptides Codex Editorial TeamReviewed July 10, 2026
Length
n/a
Class
Peptide hormone
Function
Endogenous ligand of the APJ (APLNR) receptor
Context
Cardiovascular and metabolic physiology research target

One of two natural ligands of the APJ receptor, linking cardiac function, fluid balance and adipocyte signaling.

Also known as: APLN · apelin-13 · apelin-36

Part of the Metabolic & GLP-1 peptides cluster

Overview

Apelin is an endogenous peptide hormone processed from a 77-amino-acid precursor into active fragments such as apelin-13 and apelin-36. It is one of two natural ligands of the G-protein-coupled APJ (APLNR) receptor and is studied for roles in cardiovascular function, fluid homeostasis and adipose signaling. This page is educational and not medical advice.

Source & context

Biological / chemical source: Cleaved from a 77-residue preproprotein (APLN gene)

Primary research or clinical context: Cardiovascular and metabolic physiology research target

Forms and receptor

The APLN gene encodes a preproprotein that is cleaved into several bioactive fragments, including apelin-36, apelin-17, apelin-13 and [Pyr1]-apelin-13. These share a conserved C-terminus that binds the APJ receptor, a class-A GPCR expressed in heart, vasculature, kidney and adipose tissue.

Why it is studied

Apelin research focuses on cardiac contractility, blood-pressure regulation, angiogenesis and glucose handling. Because the shorter fragments are rapidly cleared in vivo, much work explores the apelin-APJ axis and stabilized analogs as investigational tools rather than approved therapies.

FAQ about Apelin

What is Apelin?+

Apelin is an endogenous peptide hormone processed from a 77-amino-acid precursor into active fragments such as apelin-13 and apelin-36. It is one of two natural ligands of the G-protein-coupled APJ (APLNR) receptor and is studied for roles in cardiovascular function, fluid homeostasis and adipose signaling. This page is educational and not medical advice.

Is Apelin an approved medicine?+

Apelin is discussed here as a research / educational topic. Cardiovascular and metabolic physiology research target. This is not medical advice.

What is the typical length of Apelin?+

Apelin is not a classic amino-acid chain peptide in the same sense; see the profile for classification details.

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References & further reading

  1. 1.Wikipedia — Apelin
  2. 2.UniProtKB — APLN, Apelin (Human) Q9ULZ1
Disclaimer: Educational content only. Not medical advice. Not instructions for human use. Research peptides and unapproved products may be restricted or illegal to market for human consumption in your jurisdiction. Consult qualified professionals and applicable law.
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Cite this: Peptides Codex — Apelin educational profile.
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