Contribution of individual subunits to the multimeric P2X(2) receptor: estimates based on methanethiosulfonate block at T336C

Details

Serval ID
serval:BIB_10236
Type
Article: article from journal or magazin.
Collection
Publications
Title
Contribution of individual subunits to the multimeric P2X(2) receptor: estimates based on methanethiosulfonate block at T336C
Journal
Molecular pharmacology
Author(s)
Stoop R., Thomas S., Rassendren F., Kawashima E., Buell G., Surprenant A., North R.A.
ISSN
0026-895X
Publication state
Published
Issued date
1999
Peer-reviewed
Oui
Volume
56
Number
5
Pages
973-81
Language
english
Notes
Publication types: Journal Article - Publication Status: ppublish
Abstract
P2X receptors are membrane proteins that incorporate a cation-selective ion channel that can be opened by the binding of extracellular ATP. They associate as hetero- and homo-multimers of currently unknown stoichiometry. In this study, we have used Xenopus laevis oocytes to express rat P2X(2) receptor subunits, which carry a cysteine mutation at position 336. ATP-induced currents at this mutant receptor subunit were blocked by more than 90% when exposed to [2-(trimethylammonium) ethyl] methanethiosulfonate (MTSET), whereas currents from wild-type subunits were not affected. To compare mutant and wild-type channel expression, we introduced an epitope in their extracellular domains and found for both channels a similar linear relationship between antibody binding and currents induced by ATP. To study the contribution of the individual subunits to the block by MTSET, we coinjected different mixtures of wild-type and mutant-encoding mRNAs. We found that the inhibition by MTSET depended linearly on the proportion of mutant subunits, which was clearly contrary to the hypothesis that a single mutant subunit could act in a dominant fashion. Subsequent concatenation of wild-type and mutant-encoding cDNAs resulted in an inhibition by MTSET that also depended linearly on the number of mutant subunits and was independent of the position of the mutant subunit, as long as only two or three P2X(2) subunits were joined. With four or six subunits joined, however, the inhibition by MTSET became strongly position-dependent. The present results show that a "per-subunit" channel block causes the blocking effects of MTSET and they suggest that not four but maximally three subunits actively participate in the channel formation.
Keywords
Animals, DNA, Complementary, Mesylates, Mutation, Oocytes, Rats, Receptors, Purinergic P2, Xenopus laevis
Pubmed
Web of science
Create date
19/11/2007 13:00
Last modification date
20/08/2019 13:36
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