TABLE 5.

Potency (pEC₅₀), affinity (pK_a), and coupling efficacy (log τ) values for various glucagon receptor agonists measured in yeast strains containing the GPA1/Gα_i chimera and expressing the GCGR with or without RAMP2

All values are mean ± S.E. of five independent experimental repeats. N.R, no response; N.D, not determined.

^a The negative logarithm of the agonist concentration required to produce a half-maximal response.

^b The maximal response to the ligand expressed as a percentage of that obtained to glucagon in the absence of RAMP co-expression.

^c The negative logarithm of the relative equilibrium disassociation constant for each ligand generated through use of the operational model for partial agonism relative to glucagon.

^d τ is the coupling efficiency parameter, generated by comparison with the natural ligand, glucagon, using the operational model for partial agonism.