5-HT3 receptor

[1][2][3] This ion channel is cation-selective and mediates neuronal depolarization and excitation within the central and peripheral nervous systems.

Binding of the neurotransmitter 5-hydroxytryptamine (serotonin) to the 5-HT3 receptor opens the channel, which, in turn, leads to an excitatory response in neurons.

The rapidly activating, desensitizing, inward current is predominantly carried by sodium and potassium ions.

The 5-HT3C, 5-HT3D and 5-HT3E genes tend to show peripherally restricted pattern of expression, with high levels in the gut.

In patients treated with chemotherapeutic drugs, certain polymorphism of the HTR3B gene could predict successful antiemetic treatment.

The 5-HT3 receptor is expressed throughout the central and peripheral nervous systems and mediates a variety of physiological functions.

[14] On a cellular level, it has been shown that postsynaptic 5-HT3 receptors mediate fast excitatory synaptic transmission in rat neocortical interneurons, amygdala, and hippocampus, and in ferret visual cortex.

Figure 1. The subunits are assembled as a pentamer (right) and each subunit has four transmembrane domains (left).
Figure 2. Structure of the mouse 5HT3 receptor gene , showing its 9 exons (E1-E9), corresponding to the exons shown in the cDNA below. The 5' ends of exons 2, 6, and 9 have alternative splice sites. Figure drawn to scale. Modified after Uetz et al. 1994. [ 12 ]
Figure 3. The cDNA sequence of the mouse 5HT3 receptor . The cDNA encodes a 122 nucleotide 5' UTR and a ~510 nucleotide 3' UTR. Boxes indicate exons and the numbers below the exons indicate their length. For instance, the first exon encodes 22 amino acids plus one nucleotide belonging to a split codon with another 2 nucleotides encoded by the next exon. M1-4 indicate the transmembrane helices and C-C indicates the Cysteine loop. Modified after Uetz et al. 1994 [ 12 ]