The figure above shows a model of a ligand precursor being cleaved to produce an active ligand that binds to a specific receptor. Which of the following is most likely to reduce the binding of the active ligand to its receptor?

Receptors are very specific to their corresponding ligand. If a mutation caused a change in the binding site so that the location is polar instead of nonpolar, it is likely that the ligand would no longer be able to bind.

Changes to the cytoskeletal attachment or membrane might affect the location or placement of the receptor protein, but it would probably not change binding properties.

A larger amount of the precursor form of the ligand does not affect binding either. In fact, this would likely result in increased cleavage and therefore an increase in binding rather than a reduction.