Partial agonism and the two-state model of receptor activation

Partial agonism and the two-state model of receptor activation 

Agonists that show sub-maximal activation of a receptor, even at saturating concentrations, are called partial agonists . How can an agonist be partial  

The active fraction of the receptor comprises the free and the ligand-associated active forms  

The expression that that quantitatively describes the active fraction as a function of the ligand concentrationcan quite easily be derived using the equilibrium equations, together with the two equations above  

I will post an Excel spreadsheet on the course website that will allow you to play a bit with the parameters and see how they affect the resulting curve. 

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