Melatonin receptors are coupled to the intracellular effectors via GTP-binding proteins. In the presence of GTP or non-hydrolysable GTP derivatives affinity of the melatonin receptors for 125I-melatonin is decreased (15). The effects of melatonin in the pituitary, including inhibition of LH release and the effects on 2nd messengers are abolished after preincubation with pertussis toxin (PTX; 27). This indicates that the receptors are coupled to G-protein(s) belonging to the Gi family. Also the effects of melatonin in SCN are mediated by Gi: preincubation with PTX blocks the effect of melatonin on spontaneous electric activity (8). Gi family consists of 5 subspecies: 3 Gi and 2 G0 proteins (2,17). It is not clear which of these G proteins is involved in transduction of the melatonin signal.
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Salvation For The Sleep Deprived The Ultimate Guide To Sleeping, Napping, Resting And Restoring Your Energy. Of the many things that we do just instinctively and do not give much of a thought to, sleep is probably the most prominent one. Most of us sleep only because we have to. We sleep because we cannot stay awake all 24 hours in the day.