Apelin-36(rat, mouse) TFA is an endogenous orphan G protein-coupled receptor APJ agonist. Apelin-36(rat, mouse) TFA binds to APJ receptors with an IC 50 of 5.4 nM, and potently inhibits cAMP production with an EC 50 of 0.52 nM. Apelin-36(rat, mouse) TFA blocks entry of some HIV-1 and HIV-2 strains into NP-2/CD4 cells expressing APJ.