Unifying themes of major receptor superfamilies: Provide and explain 2 examples of each of the following processes, making reference to ion channels, G-coupled protein receptors, tyrosine kinase receptors and/or nuclear receptors. You can provide examples from different receptors types for different processes How binding of an agonist to its receptor initiates a pharmacodynamic response (biochemical/molecular mechanism). How receptor activation activates intracellular signaling pathways and/or effector molecules (cellular mechanism). How different types of receptors within the same family can, despite a high degree of homology and shared functionality, generate distinct pharmacodynamic effects (i.e. modulate different signaling pathways in different ways or in different cells/tissues). How receptors and/or receptor-mediated signaling are down-regulated following continued activation by an endogenous or xenobiotic agonist (desensitization). .