Fig. 1. MRAP2 potentiates the ghrelin-stimulated and inhibits the constitutive activity of GHSR1a.

(A) Ghrelin-stimulated IP accumulation in CHO cells expressing GHSR1a with empty vector or increasing amount of MRAP2. Results are shown in fold increase over baseline and represent the mean + SEM of 3 independent experiments performed in triplicate. (B) Ghrelin-stimulated IP accumulation in CHO cells expressing GHSR1a with empty vector or MRAP2 at a 1/20 ratio. Results are shown as the percentage of the maximal response in cells expressing GHSR1a and empty vector and represent the mean + SEM of 3 independent experiments performed in triplicate. (C) Measurement of IP accumulation over 1 hour in the presence of lithium and absence of agonist in cells transfected with increasing amount of GHSR1a and either empty vector or MRAP2. Empty vector and MRAP2 concentration were kept constant. Data represent the mean + SEM of 3 independent experiments performed in triplicate. (D) Ghrelin-stimulated IP accumulation in CHO cells expressing GHSR1a(A204E) with empty vector or MRAP2. Measurement of IP₃ production over 1 hour in the presence of lithium and absence of agonist in cells transfected with GHSR1a and empty vector, MRAP2 or the indicated MRAP2 mutant. Error are mean +/− SEM. Data represent the results of at least 3 independent experiments. Statistical analysis was done using multiple T-test (one unpaired T-test per condition). ***p<0.001, *p<0.05.