Better Together

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Science  01 Nov 2013:
Vol. 342, Issue 6158, pp. 535
DOI: 10.1126/science.342.6158.535-d

G protein (heterotrimeric guanine nucleotide–binding protein)–coupled receptors (GPCRs) are one of the most abundant and most important families of integral membrane proteins, and evidence continues to accumulate showing that they can function as heterodimers. These have been especially promising findings because GPCRs are common drug targets, and heteromers could offer an additional means of tuning drug specificity. Baba et al. show that in mice, type 1 and type 2 melatonin receptors function together in the retina to produce physiological increases in the sensitivity of photoreceptors to light during the night. Tagged receptors were localized in complexes in the retina, and the loss of one receptor subtype or the other prevented melatonin's effects in the retina. Furthermore, the heteromeric receptors coupled to a signaling pathway distinct from that activated by the monomeric receptors, increasing the efficacy and potency of the receptor complex in the activation of phospholipase C and protein kinase C. An ability to replenish such melatonin signaling could be useful in limiting age-related loss of retinal function, as can occur in macular degeneration.

Sci. Signal. 6, ra89 (2013).

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