Allosteric modulator

Allosteric modulators are drugs that influence a protein’s response to ligand binding; this could mean enhancing or reducing a receptor’s response to agonist, or substrate turnover by an enzyme, or molecules transported by a transporter protein. Positive allosteric modulators enhance or increase the size or rate of response, while negative allosteric modulators reduce the size or rate of response. There is no competition between the allosteric modulator and the ligand binding to the agonist binding site, active site or transporter site, although there may be an allosteric effect that results in reduced binding of the primary ligand; this can give the appearance of competition, but it is straightforward to differentiate in carefully-done experiments.