Peptide Database

APLNR ligand · apelin-13

Apelin is an endogenous peptide that acts as the ligand for the APJ receptor (APLNR), a GPCR expressed throughout the cardiovascular system. It improves cardiac output and vascular tone through both positive inotropy and vasodilation, increases nitric oxide production, and reduces oxidative stress. Research focuses on heart failure, pulmonary arterial hypertension, and its potential to replace or complement established cardiac peptides.

ET-1 · Big endothelin-1

Endothelin-1 (ET-1) is a 21-amino-acid vasoconstrictor peptide produced primarily by vascular endothelial cells. It is the most potent endogenous vasoconstrictor known, acting through ETA and ETB receptors on vascular smooth muscle and endothelium. Elevated ET-1 is implicated in pulmonary arterial hypertension, heart failure, and renal disease — driving the development of endothelin receptor antagonists (bosentan, ambrisentan, macitentan) as clinical drugs.

Serelaxin · H2 relaxin

Relaxin-2 is an endogenous peptide hormone structurally related to insulin, primarily known for its role in pregnancy (cervical ripening, joint laxity). Research discovered its potent anti-fibrotic properties — it remodels collagen networks in heart, kidney, lung, and liver — making it a leading candidate for fibrosis and acute heart failure. Serelaxin (recombinant relaxin) reached Phase 3 trials for acute heart failure with promising early signals but did not meet primary endpoints.