Baines, A;
Parkinson, K;
Sim, JA;
Bragg, L;
Thompson, CRL;
North, RA;
(2013)
Functional Properties of Five Dictyostelium discoideum P2X Receptors.
Journal of Biological Chemistry
, 288
(29)
pp. 20992-21000.
10.1074/jbc.m112.445346.
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Abstract
The Dictyostelium discoideum genome encodes five proteins that share weak sequence similarity with vertebrate P2X receptors. Unlike vertebrate P2X receptors, these proteins are not expressed on the surface of cells, but populate the tubules and bladders of the contractile vacuole. In this study, we expressed humanized cDNAs of P2XA, P2XB, P2XC, P2XD, and P2XE in human embryonic kidney cells and altered the ionic and proton environment in an attempt to reflect the situation in amoeba. Recording of whole-cell membrane currents showed that four receptors operated as ATP-gated channels (P2XA, P2XB, P2XD, and P2XE). At P2XA receptors, ATP was the only effective agonist of 17 structurally related putative ligands that were tested. Extracellular sodium, compared with potassium, strongly inhibited ATP responses in P2XB, P2XD, and P2XE receptors. Increasing the proton concentration (pH 6.2) accelerated desensitization at P2XA receptors and decreased currents at P2XD receptors, but increased the currents at P2XB and P2XE receptors. Dictyostelium lacking P2XA receptors showed impaired regulatory volume decrease in hypotonic solution. This phenotype was readily rescued by overexpression of P2XA and P2XD receptors, partially rescued by P2XB and P2XE receptors, and not rescued by P2XC receptors. The failure of the nonfunctional receptor P2XC to restore the regulatory volume decrease highlights the importance of ATP activation of P2X receptors for a normal response to hypo-osmotic shock, and the weak rescue by P2XB and P2XE receptors indicates that there is limited functional redundancy among Dictyostelium P2X receptors.
| Type: | Article |
|---|---|
| Title: | Functional Properties of Five Dictyostelium discoideum P2X Receptors |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1074/jbc.m112.445346 |
| Publisher version: | https://doi.org/10.1074/jbc.m112.445346 |
| Language: | English |
| Additional information: | Copyright © 2013 by The American Society for Biochemistry and Molecular Biology, Inc. Creative Commons Attribution Unported License (https://creativecommons.org/licenses/by/3.0/) applies to Author Choice Articles. |
| Keywords: | ATP, Ion Channels, Purinergic Agonists, Purinergic Receptor, Vacuolar Acidification, Dictyostelium, Osmoregulation, P2X Receptor |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > Div of Biosciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > Div of Biosciences > Genetics, Evolution and Environment |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10066472 |
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