Some of the key antagonists at the apelin receptor and their binding affinities

MM54, an antagonist at the β-arrestin and internalization pathway, consists of a cyclized peptide based around the RPRL motif. MM54 has been tested for selectivity (Bowes et al., 2012) against over 50 GPCRs (including the most closely related angiotensin II receptor AT1) and ion channels. ALX40-4C and protamine both consist of a series of positively charged amino acids and display low binding affinities and likely low selectivity for the apelin receptor.

LigandActionBinding AffinityUnitsReferences
MM54Antagonist8.2pKiMacaluso et al., 2011
ALX40-4CAntagonist5.5pIC50Zhou et al., 2003b
ML221AntagonistMaloney et al., 2012
ProtamineAntagonist6.4pKiLe Gonidec et al., 2017