Dopamine’s unusual binding technique

D2 dopamine receptors are the principal targets for antipsychotic drugs for the treatment of schizophrenia, and offer possibilities for treating depression and Parkinson’s disease. However, molecular-level understanding of these receptors is limited, and many available drugs cause serious side-effects as a result of activity at other dopamine receptors. Here, Bryan Roth and colleagues report the crystal structure of the D2 receptor in complex with the antipsychotic drug risperidone. This structure shows an unusual binding mode of the drug, distinct from those observed in the related D3 and D4 receptors, whereby a hydrophobic patch formed by a tryptophan residue regulates the entry and exit of the drug. Mutation at this position reduces the drug residence time, which is believed to be related to side-effects of common antipsychotics. This work hints at ways to develop safer antipsychotic drugs that are selective for D2.