Orphan GPCR SP9155 agonist P550 (mouse, rat) (26RFa (mouse, rat)) is an orphan GPCR with an orexigenic effect belonging to the RFamide peptide family. It acts as the cognate ligand for the mouse orphan receptor GPR103, which is also known as SP9155 or AQ27.
CGP 55845 is a potent, selective GABAB receptor antagonist (IC50 = 5 nM) that prevents agonist binding (pKi = 8.35) and inhibits GABA and glutamate release (pEC50 values are 8.08 and 7.85 respectively).