Mix and Match: Heterodimers and Opioid Tolerance

Heterodimerization of G-protein coupled receptors has become increasingly recognized as a valuable mechanism to increase receptor diversity. Heterodimers have been observed in the opioid receptor family, but one of the most intriguing is that formed between mu and delta opioid receptors. In this issue of Neuron He et al. present evidence further implicating these heterodimers in morphine tolerance.