P2X receptor intermediate activation states have altered nucleotide selectivity

Purinergic P2X receptors are widely distributed in the nervous system and are known to play roles in primary afferent transmission and central respiratory regulation. They are trimeric membrane proteins, with the extracellular domain that provides three intersubunit ATP binding sites. We expressed t...

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Bibliographic Details
Published in:The Journal of neuroscience 2013-09, Vol.33 (37), p.14801-14808
Main Authors: Browne, Liam E, North, R Alan
Format: Article
Language:English
Subjects:
Adenosine Diphosphate
Adenosine Triphosphate - analogs & derivatives
Adenosine Triphosphate - pharmacology
Animals
Green Fluorescent Proteins - genetics
HEK293 Cells
Humans
Nucleotides - metabolism
Nucleotides - pharmacology
Patch-Clamp Techniques
Platelet Aggregation Inhibitors - pharmacology
Purinergic P2X Receptor Antagonists - pharmacology
Pyridines - pharmacology
Rats
Receptors, Purinergic P2X2 - genetics
Receptors, Purinergic P2X2 - metabolism
Receptors, Purinergic P2X7 - genetics
Receptors, Purinergic P2X7 - metabolism
Tetrazoles - pharmacology
Time Factors
Transfection
Ultraviolet Rays
Uridine Triphosphate
Zinc - pharmacology
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Summary:Purinergic P2X receptors are widely distributed in the nervous system and are known to play roles in primary afferent transmission and central respiratory regulation. They are trimeric membrane proteins, with the extracellular domain that provides three intersubunit ATP binding sites. We expressed the rat P2X7 receptor in human embryonic kidney cells and measured membrane currents before and after photo-affinity labeling with the agonist 2'(3')-O-(4-benzoylbenzoyl)-ATP (BzATP). After tethering BzATP with ultraviolet light, a persistent current remained after washing out the agonist. Additional current could now be elicited by other nucleotides (CTP and ADP) that are not normally effective as P2X receptor agonists. Similar results were obtained at P2X2 receptors even without previous agonist tethering: exposure to low concentrations of ATP caused the receptor to become sensitive to activation by CTP and ADP. The results show that ATP binding to the first of the three binding sites causes a conformational change to an intermediate closed state that shows increased effectiveness of pyrimidine and diphosphate nucleotide analogs.
ISSN:0270-6474
1529-2401
1529-2401
DOI:10.1523/jneurosci.2022-13.2013