Allosteric modulators can restore function in an amino acid neurotransmitter receptor by slightly altering intra-molecular communication pathways

Mutations, even if not directly in the ligand binding sites of proteins, can lead to disease. In cell surface receptors, this can happen if they uncouple conformational changes that take place upon agonist (or antagonist) binding to the extracellular domain and the intracellular response. Uncoupling can take place by disrupting a major allosteric propagation pathway between the extra- and intracellular domains. Here I provide a mechanistic explanation: I first describe how propagation takes place; second, what can happen in the presence of a disease-related mutation which is distant from the binding site; and finally, how drugs may overcome this disruption and rescue function. The mutations in the glycine receptor a1 subunit (alpha 1R271Q/L) which cause the neuromotor disorder hyperekplexia are on example of such allosteric mutations. In this issue of the BJP, Shan et al. show that normal function was restored to these mutant receptors by substitution of the segment which contained the mutated position, by a homologous one. An allosteric drug could mimic the effects of such substitution. Within this framework, I highlight the advantages of allosteric drugs and the challenges in their design.