Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
Biophys J
2007 Aug 01;933:846-58. doi: 10.1529/biophysj.106.103614.
Show Gene links
Show Anatomy links
Influence of extracellular monovalent cations on pore and gating properties of P2X7 receptor-operated single-channel currents.
Riedel T, Schmalzing G, Markwardt F.
???displayArticle.abstract???
Using the patch-clamp method, we studied the influence of external alkali and organic monovalent cations on the single-channel properties of the adenosine triphosphate (ATP)-activated recombinant human P2X(7) receptor. The slope conductance of the hP2X(7) channel decreased and the reversal potential was shifted to more negative values as the ionic diameter of the organic test cations increased. From the relationship between single-channel conductance and the dimensions of the inward current carrier, the narrowest portion of the pore was estimated to have a mean diameter of approximately 8.5 A. Single-channel kinetics and permeation properties remained unchanged during receptor activation by up to 1 mM ATP(4-) for >1 min, arguing against a molecular correlate of pore dilation at the single P2X(7) channel level. Substitution of extracellular Na(+) by any other alkali or organic cation drastically increased the open probability of the channels by prolonging the mean open time. This effect seems to be mediated allosterically through an extracellular voltage-dependent Na(+) binding site with a K(d) of approximately 5 mM Na(+) at a membrane potential of -120 mV. The modulation of the ATP-induced hP2X(7) receptor gating by extracellular Na(+) could be well described by altering the rate constant from the open to the neighboring closed state in a C-C-C-O kinetic receptor model. We suggest that P2X(7) receptor-induced depolarization and associated K(+)-efflux may reduce Na(+) occupancy of the regulatory Na(+) binding site and thus increase the efficacy of ATP(4-) in a feed-forward manner in P2X(7) receptor-expressing cells.
Amstrup,
P2X7 receptor activates extracellular signal-regulated kinases ERK1 and ERK2 independently of Ca2+ influx.
2003, Pubmed
Amstrup,
P2X7 receptor activates extracellular signal-regulated kinases ERK1 and ERK2 independently of Ca2+ influx.
2003,
Pubmed Boldt,
Glu496Ala polymorphism of human P2X7 receptor does not affect its electrophysiological phenotype.
2003,
Pubmed
,
Xenbase Bretschneider,
Nonselective cationic currents elicited by extracellular ATP in human B-lymphocytes.
1995,
Pubmed Chen,
Extracellular ATP increases NH4+ permeability in human lymphocytes by opening a P2Z purinoceptor operated ion channel.
1994,
Pubmed Chessell,
Properties of the pore-forming P2X7 purinoceptor in mouse NTW8 microglial cells.
1997,
Pubmed Cockcroft,
ATP induces nucleotide permeability in rat mast cells.
1979,
Pubmed Colquhoun,
Binding, gating, affinity and efficacy: the interpretation of structure-activity relationships for agonists and of the effects of mutating receptors.
1998,
Pubmed Colquhoun,
Relaxation and fluctuations of membrane currents that flow through drug-operated channels.
1977,
Pubmed Ding,
Ion permeation and block of P2X(2) purinoceptors: single channel recordings.
1999,
Pubmed Ding,
Single channel properties of P2X2 purinoceptors.
1999,
Pubmed
,
Xenbase Egan,
Contribution of calcium ions to P2X channel responses.
2004,
Pubmed Elliott,
Membrane phosphatidylserine distribution as a non-apoptotic signalling mechanism in lymphocytes.
2005,
Pubmed Evans,
Ionic permeability of, and divalent cation effects on, two ATP-gated cation channels (P2X receptors) expressed in mammalian cells.
1996,
Pubmed Faria,
Are second messengers crucial for opening the pore associated with P2X7 receptor?
2005,
Pubmed Ferrari,
The P2X7 receptor: a key player in IL-1 processing and release.
2006,
Pubmed Jiang,
N-methyl-D-glucamine and propidium dyes utilize different permeation pathways at rat P2X(7) receptors.
2005,
Pubmed Khakh,
Neuronal P2X transmitter-gated cation channels change their ion selectivity in seconds.
1999,
Pubmed Khakh,
Dynamic selectivity filters in ion channels.
1999,
Pubmed Klapperstück,
Characteristics of P2X7 receptors from human B lymphocytes expressed in Xenopus oocytes.
2000,
Pubmed
,
Xenbase Lim,
Pain.
1970,
Pubmed Löhn,
Sodium block and depolarization diminish P2Z-dependent Ca2+ entry in human B lymphocytes.
2001,
Pubmed Ma,
Extracellular sodium regulates airway ciliary motility by inhibiting a P2X receptor.
1999,
Pubmed Markwardt,
Purinoceptor-operated cationic channels in human B lymphocytes.
1997,
Pubmed Negulyaev,
Block by extracellular Mg2+ of single human purinergic P2X4 receptor channels expressed in human embryonic kidney cells.
2000,
Pubmed Neher,
Correction for liquid junction potentials in patch clamp experiments.
1992,
Pubmed North,
Molecular physiology of P2X receptors.
2002,
Pubmed Nuttle,
Differential activation of cation channels and non-selective pores by macrophage P2z purinergic receptors expressed in Xenopus oocytes.
1994,
Pubmed
,
Xenbase Pelegrin,
Pannexin-1 mediates large pore formation and interleukin-1beta release by the ATP-gated P2X7 receptor.
2006,
Pubmed Petrou,
P2X7 purinoceptor expression in Xenopus oocytes is not sufficient to produce a pore-forming P2Z-like phenotype.
1997,
Pubmed
,
Xenbase Rassendren,
The permeabilizing ATP receptor, P2X7. Cloning and expression of a human cDNA.
1997,
Pubmed Riedel,
Kinetics of P2X7 receptor-operated single channels currents.
2007,
Pubmed
,
Xenbase Schilling,
Maitotoxin and P2Z/P2X(7) purinergic receptor stimulation activate a common cytolytic pore.
1999,
Pubmed Schubert,
Multiple ligand-ion solutions: a guide for solution preparation and computer program understanding.
1996,
Pubmed Smart,
P2X7 receptor cell surface expression and cytolytic pore formation are regulated by a distal C-terminal region.
2003,
Pubmed
,
Xenbase Steinberg,
ATP4- permeabilizes the plasma membrane of mouse macrophages to fluorescent dyes.
1987,
Pubmed Surprenant,
The cytolytic P2Z receptor for extracellular ATP identified as a P2X receptor (P2X7).
1996,
Pubmed Virginio,
Pore dilation of neuronal P2X receptor channels.
1999,
Pubmed Virginio,
Kinetics of cell lysis, dye uptake and permeability changes in cells expressing the rat P2X7 receptor.
1999,
Pubmed Wiley,
The ATP4- receptor-operated channel (P2Z class) of human lymphocytes allows Ba2+ and ethidium+ uptake: inhibition of fluxes by suramin.
1993,
Pubmed
