Figure 7
From: Identification of an allatostatin C signaling system in mollusc Aplysia
Activation of Aplysia AstC and related peptides on putative receptors determined using IP1 accumulation assay. (A,B) Screening of potential activation of peptide ligands on putative receptors (AstC-R and Class-A_GPCR1) using two concentration: 10–10 M and 10–5 M. At 10–10 M, a peptide activated a receptor minimally, if at all, so it is used as a control. (A) AstC, AstC' (AstC without the disulfide bridge), AstCG-DP, Aplysia SPTR (apSPTR-GP-DP2). (B) AstCs from four other molluscan species: AstC-T (Theba pisana), AstC-D (Deroceras reticulatum), AstC-C (Crassostrea gigas) and AstC-L (Lottia giagantea). AstC, AstC-T, AstC-D, AstC-C and AstC-L on AstC-R: n = 6, AstC' on AstC-R: n = 5; n = 3 for all other tests. AstC and AstC' significantly increased IP1 concentration when acting on AstC-R, suggesting that AstC and AstC' are ligands for AstC-R. AstC-T, AstC-D, AstC-C and AstC-L also significantly increased IP1 concentration when acting on AstC-R. In contrast, AstCG-DP and SPTR did not activate AstC-R significantly. Moreover, Class-A_GPCR1 did not respond significantly to any of the peptides. Paired t-test, *, P < 0.05, **, P < 0.01, *** P < 0.001, error bar: SEM. (C–E) Representative examples of dose response curves of the activation of AstC-R by Aplysia AstC (C), AstC' (D), and AstC-T, AstC-D, AstC-C and AstC-L (E). Each data point is from two wells. Error bars, SEM. (F) Comparison of log[EC50] from the six peptides (n = 3 for each) shown in (C–E). One-way ANOVA, F(5, 12) = 8.47, P < 0.01. Bonferroni post-hoc test: *, P < 0.05, ***, P < 0.001. (G) Sequences of all peptides tested and summary of the average log[EC50] and EC50 on AstC-R. Cysteines in red denote the disulfide bridge in the peptide.
