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5-Hydroxytryptamine inhibits P2X2 receptor channel pore mutants
1Division of Pharmacology, National Institute of Health Sciences, Tokyo, Japan. nakazawa@nihs.go.jp
Cellular and Molecular Neurobiology
|June 29, 1999
Summary
5-Hydroxytryptamine enhances wild-type P2X2 receptor/channel currents but inhibits mutants. This suggests 5-hydroxytryptamine binds to the P2X2 receptor/channel pore, particularly at Thr330 and Asn333 residues.
Area of Science:
- Neuroscience
- Molecular Biology
- Pharmacology
Background:
- The P2X2 receptor is an ATP-gated ion channel involved in neurotransmission.
- 5-Hydroxytryptamine (serotonin) is a key neurotransmitter with diverse physiological roles.
Purpose of the Study:
- To investigate the interaction of 5-hydroxytryptamine with the P2X2 receptor/channel.
- To elucidate the specific binding sites and mechanisms of 5-hydroxytryptamine modulation on P2X2 receptor activity.
Main Methods:
- Utilized Xenopus oocytes for expressing wild-type and mutant P2X2 receptor/channels.
- Employed electrophysiological techniques to measure ionic currents mediated by P2X2 receptors.
- Investigated the effects of 5-hydroxytryptamine (10 microM) on receptor activity.
Main Results:
- 5-Hydroxytryptamine (10 microM) enhanced ionic current through wild-type P2X2 receptors.
- 5-Hydroxytryptamine (10 microM) inhibited currents in P2X2 receptor mutants T330I and N333I.
- Mutations neutralizing Thr330 or Asn333 revealed a high-affinity inhibitory binding site for 5-hydroxytryptamine.
Conclusions:
- The findings suggest that 5-hydroxytryptamine interacts with the P2X2 receptor/channel at the channel pore.
- Neutralization of Thr330 or Asn333 residues is critical for the inhibitory action of 5-hydroxytryptamine.
- This implies a specific interaction site within the pore for 5-hydroxytryptamine binding.