Regulation of ATP-gated P2X channels: from redox signaling to interactions with other proteins.
CONCLUSIONS
The family of purinergic P2X receptors (P2XRs) is a part of ligand-gated superfamily of channels activated by extracellular adenosine-5'-triphosphate. P2XRs are present in virtually all mammalian tissues as well as in tissues of other vertebrate and nonvertebrate species and mediate a large variety of functions, including fast transmission at central synapses, contraction of smooth muscle cells, platelet aggregation, and macrophage activation to proliferation and cell death.


BACKGROUND
The recent solving of crystal structure of the zebrafish P2X4.1R is a major advance in the understanding of structural correlates of channel activation and regulation. Combined with growing information obtained in the post-structure era and the reinterpretation of previous work within the context of the tridimensional structure, these data provide a better understanding of how the channel operates at the molecular levels.


RESULTS
This review focuses on the relationship between redox signaling and P2XR function. We also discuss other allosteric modulation of P2XR gating in the physiological/pathophysiological context. This includes the summary of extracellular actions of trace metals, which can be released to the synaptic cleft, pH decrease that happens during ischemia and inflammation, and calcium, an extracellular and intracellular messenger.


CONCLUSIONS
Our evolving understanding of activation and regulation of P2XRs is helpful in clarifying the mechanism by which these channels trigger and modulate cellular functions. Further research is required to identify the signaling pathways contributing to the regulation of the receptor activity and to develop novel and receptor-specific allosteric modulators, which could be used in vivo with therapeutic potential.
1 Section on Cellular Signaling, Program in Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health , Bethesda, Maryland.
Stanko S
SS
Stojilkovic
Elías
E
Leiva-Salcedo
Milos B
MB
Rokic
Claudio
C
Coddou
D000255:Adenosine Triphosphate / Q000378:metabolism*; D000494:Allosteric Regulation; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D003300:Copper / Q000378:metabolism; D005110:Extracellular Space / Q000378:metabolism; D006801:Humans; D042541:Intracellular Space / Q000378:metabolism; D008274:Magnesium / Q000378:metabolism; D011485:Protein Binding; D011494:Protein Kinases / Q000378:metabolism; D055503:Protein Multimerization; D011522:Protons; D058469:Receptors, Purinergic P2X / Q000737:chemistry / Q000378:metabolism*; D015398:Signal Transduction; D015032:Zinc / Q000378:metabolism
D002352:Carrier Proteins; D011522:Protons; D058469:Receptors, Purinergic P2X; D003300:Copper; D000255:Adenosine Triphosphate; D011494:Protein Kinases; D008274:Magnesium; D015032:Zinc; D002118:Calcium