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Biochemical and functional evidence for heteromeric assembly of P2X 1 and P2X 4 subunits
Author(s) -
Nicke Annette,
Kerschensteiner Daniel,
Soto Florentina
Publication year - 2005
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.2004.02939.x
Subject(s) - homomeric , receptor , xenopus , ligand gated ion channel , ion channel , suramin , cys loop receptors , biology , protein subunit , biophysics , microbiology and biotechnology , extracellular , biochemistry , chemistry , acetylcholine receptor , nicotinic acetylcholine receptor , gene
P2X receptors are ligand‐gated ion channels activated by extracellular ATP. In expression systems, P2X subunits form homo‐ and heterotrimeric receptors. Heteromerization is also likely to occur in vivo as (i) most P2X subunits show overlapping distribution in different tissues and (ii) the functional properties of many native P2X receptors differ from those of heterologously expressed homomeric receptors. Here, we used the Xenopus laevis oocyte expression system to test for heteromerization of P2X 1 and P2X 4 subunits. Upon co‐injection, P2X 4 subunits were co‐purified with hexahistidyl‐tagged P2X 1 subunits indicating heteromerization. Blue native polyacrylamide gel electrophoresis (BN‐PAGE) analysis of these P2X complexes excluded artificial aggregation and confirmed that both subunits were present in trimeric complexes of the same size. Two‐electrode voltage‐clamp experiments revealed functional P2X receptors with kinetic properties resembling homomeric P2X 4 receptors and a pharmacological profile similar to homomeric P2X 1 receptors. Thus, application of α,β‐methylene ATP evoked a slowly desensitizing current sensitive to the antagonists suramin and 2′,3′‐ O ‐(2,4,6‐trinitrophenyl)‐ATP. This study provides for the first time biochemical and functional evidence for the formation of heteromeric P2X 1+4 receptors. These receptors may account for native P2X mediated responses that until now could not be correlated with previously described recombinant P2X receptors.