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.
| Ligand | Action | Binding Affinity | Units | References |
|---|---|---|---|---|
| MM54 | Antagonist | 8.2 | pKi | Macaluso et al., 2011 |
| ALX40-4C | Antagonist | 5.5 | pIC50 | Zhou et al., 2003b |
| ML221 | Antagonist | — | — | Maloney et al., 2012 |
| Protamine | Antagonist | 6.4 | pKi | Le Gonidec et al., 2017 |