Figure 3.

Specific [¹²⁵I]‐orexin‐A (OxA) binding to CHO‐S–OX₁ receptor (OX1R) cells in the presence of increasing concentrations of unlabelled orexin‐B, S18A/N20A and S18A/T27A peptides (A) and determination of the inhibition of cellular growth induced by increasing concentrations of orexin‐B, S18A/N20A (B, C) and S18A/T27A (B, D) peptides in CHO‐S–OX1R cells. (A) CHO‐S–OX1R cells were incubated with the indicated concentrations of orexin‐B, S18A/N20A and S18A/T27A. Results are expressed as % of radioactivity specifically bound in the absence of added unlabelled peptide. (B) CHO‐S–OX1R cells were incubated with the indicated concentrations of orexin‐B, S18A/N20A and S18A/T27A, and cells were counted after 48 h incubation. Results are expressed as % of total viable cells. (C, D) Increasing concentrations of orexin‐B were incubated together with the following concentrations of S18A/N20A mutant (C): 0, 10 nM, 100 nM, 1 μM, 10 μM, or S18A/T27A mutant (D). Each point is the mean of three separate experiments. For clarity, SEM are not indicated; they were always below 15% of mean values.