Once a ligand has bound to a receptor, it will continue to generate its response. In order to stop that response, the ligand must be removed or inactivated in some way

Question

Describe the different ways this may be accomplished, along with features of each method.

What will be an ideal response?

Answer 1

Answer: One way in which ligands will leave their receptor is if the surrounding concentration decreases. This can be achieved by having the ligand leave via the blood where it can be degraded by the liver or kidneys, or by having adjacent cells take up excess ligand. If using the blood, this process will take a little longer. Using adjacent cells is certainly more rapid, but these cells may not always be located in close enough proximity. A third method for reducing local concentrations uses enzymes to digest any free ligand. Again, this is more rapid, but does require the enzymes to be present. Alternatively, the whole receptor-ligand complex can be endocytosed and digested within the cell. It is also possible to inactivate the functional domains of the receptor so that the effects of the ligand are no longer occurring intracellularly.