FIGURE 5.

Effect of F203^3.40C mutation on sauvagine binding. A, amino acid sequences of sauvagine and Tyr⁰-sauvagine. The amino acids in gray boxes interact with the second extracellular loop of CRF₁R (15). B, competition binding isotherms of sauvagine at the ΔCys + F203C, before and after its reaction with MTSEA. The means and S.E. (duplicate determination) are shown from a representative experiment performed four times with similar results. The affinities (−logK_i) of sauvagine, determined from these experiments, are 7.37 ± 0.11 and 8.20 ± 0.15, for the ΔCys + F203C and the MTSEA-treated ΔCys + F203C, respectively.