title: A consensus segment in the M2 domain of the hP2X(7) receptor shows ion channel activity in planar lipid bilayers and in biological membranes.
abstract: The P2X(7) receptor (P2X(7)R) is an ATP-gated, cation-selective channel permeable to Na(+), K(+) and Ca(2+). This channel has also been associated with the opening of a non-selective pore that allows the flow of large organic ions. However, the biophysical properties of the P2X(7)R have yet to be characterized unequivocally. We investigated a region named ADSEG, which is conserved among all subtypes of P2X receptors (P2XRs). It is located in the M2 domain of hP2X(7)R, which aligns with the H5 signature sequence of potassium channels. We investigated the channel forming ability of ADSEG in artificial planar lipid bilayers and in biological membranes using the cell-attached patch-clamp techniques. ADSEG forms channels, which exhibit a preference for cations. They are voltage independent and show long-term stability in planar lipid bilayers as well as under patch-clamping conditions. The open probability of the ADSEG was similar to that of native P2X(7)R. The conserved part of the M2 domain of P2X(7)R forms ionic channels in planar lipid bilayers and in biological membranes. Its electrophysiological characteristics are similar to those of the whole receptor. Conserved and hydrophobic part of the M2 domain forms ion channels.
authors.affiliation: Oswaldo Cruz Foundation, Oswaldo Cruz Institute, Laboratory of Cellular Communication, Av. Brazil 4365, 21045-900, Rio de Janeiro, Brazil.
authors.forename: Cristina Alves Magalhães
authors.initials: CA
authors.lastname: de Souza
authors.forename: Pedro Celso Nogueira
authors.initials: PC
authors.lastname: Teixeira
authors.forename: Robson Xavier
authors.initials: RX
authors.lastname: Faria
authors.forename: Oxana
authors.initials: O
authors.lastname: Krylova
authors.forename: Peter
authors.initials: P
authors.lastname: Pohl
authors.forename: Luiz Anastacio
authors.initials: LA
authors.lastname: Alves
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D015640:Ion Channel Gating; D017136:Ion Transport; D008051:Lipid Bilayers / Q000737:chemistry / Q000378:metabolism*; D008564:Membrane Potentials; D008958:Models, Molecular; D008969:Molecular Sequence Data; D018408:Patch-Clamp Techniques; D017434:Protein Structure, Tertiary; D058486:Receptors, Purinergic P2X7 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction
chemical_list: D008051:Lipid Bilayers; D058486:Receptors, Purinergic P2X7; D000255:Adenosine Triphosphate