Responses of rat P2X2 receptors to ultrashort pulses of ATP provide insights into ATP binding and channel gating
To gain insight into the way that P2X2 receptors localized at synapses might function, we explored the properties of outside-out patches containing many of these channels as ATP was very rapidly applied and removed. Using a new method to calibrate the speed of exchange of solution over intact patche...
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todo:paper_00221295_v130_n2_p183_Moffatt2023-10-03T14:27:22Z Responses of rat P2X2 receptors to ultrashort pulses of ATP provide insights into ATP binding and channel gating Moffatt, L. Hume, R.I. adenosine triphosphate n methyl dextro aspartic acid receptor purine P2X2 receptor adenosine triphosphate purine P2 receptor purine P2X2 receptor allosterism article channel gating embryo human human cell kinetics synapse animal biological model cell line dose response drug effect electrophysiology patch clamp physiology protein binding rat time Adenosine Triphosphate Animals Cell Line Dose-Response Relationship, Drug Electrophysiology Humans Ion Channel Gating Models, Biological Patch-Clamp Techniques Protein Binding Rats Receptors, Purinergic P2 Synapses Time Factors To gain insight into the way that P2X2 receptors localized at synapses might function, we explored the properties of outside-out patches containing many of these channels as ATP was very rapidly applied and removed. Using a new method to calibrate the speed of exchange of solution over intact patches, we were able to reliably produce applications of ATP lasting <200 μs. For all concentrations of ATP, there was a delay of at least 80 μs between the time when ATP arrived at the receptor and the first detectable flow of inward current. In response to 200-μs pulses of ATP, the time constant of the rising phase of the current was ∼600 μs. Thus, most channel openings occurred when no free ATP was present. The current deactivated with a time constant of ∼60 ms. The amplitude of the peak response to a brief pulse of a saturating concentration of ATP was ∼70% of that obtained during a long application of the same concentration of ATP. Thus, ATP leaves fully liganded channels without producing an opening at least 30% of the time. Extensive kinetic modeling revealed three different schemes that fit the data well, a sequential model and two allosteric models. To account for the delay in opening at saturating ATP, it was necessary to incorporate an intermediate closed state into all three schemes. These kinetic properties indicate that responses to ATP at synapses that use homomeric P2X2 receptors would be expected to greatly outlast the duration of the synaptic ATP transient produced by a single presynaptic spike. Like NMDA receptors, P2X2 receptors provide the potential for complex patterns of synaptic integration over a time scale of hundreds of milliseconds. © The Rockefeller University Press. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_00221295_v130_n2_p183_Moffatt |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
adenosine triphosphate n methyl dextro aspartic acid receptor purine P2X2 receptor adenosine triphosphate purine P2 receptor purine P2X2 receptor allosterism article channel gating embryo human human cell kinetics synapse animal biological model cell line dose response drug effect electrophysiology patch clamp physiology protein binding rat time Adenosine Triphosphate Animals Cell Line Dose-Response Relationship, Drug Electrophysiology Humans Ion Channel Gating Models, Biological Patch-Clamp Techniques Protein Binding Rats Receptors, Purinergic P2 Synapses Time Factors |
| spellingShingle |
adenosine triphosphate n methyl dextro aspartic acid receptor purine P2X2 receptor adenosine triphosphate purine P2 receptor purine P2X2 receptor allosterism article channel gating embryo human human cell kinetics synapse animal biological model cell line dose response drug effect electrophysiology patch clamp physiology protein binding rat time Adenosine Triphosphate Animals Cell Line Dose-Response Relationship, Drug Electrophysiology Humans Ion Channel Gating Models, Biological Patch-Clamp Techniques Protein Binding Rats Receptors, Purinergic P2 Synapses Time Factors Moffatt, L. Hume, R.I. Responses of rat P2X2 receptors to ultrashort pulses of ATP provide insights into ATP binding and channel gating |
| topic_facet |
adenosine triphosphate n methyl dextro aspartic acid receptor purine P2X2 receptor adenosine triphosphate purine P2 receptor purine P2X2 receptor allosterism article channel gating embryo human human cell kinetics synapse animal biological model cell line dose response drug effect electrophysiology patch clamp physiology protein binding rat time Adenosine Triphosphate Animals Cell Line Dose-Response Relationship, Drug Electrophysiology Humans Ion Channel Gating Models, Biological Patch-Clamp Techniques Protein Binding Rats Receptors, Purinergic P2 Synapses Time Factors |
| description |
To gain insight into the way that P2X2 receptors localized at synapses might function, we explored the properties of outside-out patches containing many of these channels as ATP was very rapidly applied and removed. Using a new method to calibrate the speed of exchange of solution over intact patches, we were able to reliably produce applications of ATP lasting <200 μs. For all concentrations of ATP, there was a delay of at least 80 μs between the time when ATP arrived at the receptor and the first detectable flow of inward current. In response to 200-μs pulses of ATP, the time constant of the rising phase of the current was ∼600 μs. Thus, most channel openings occurred when no free ATP was present. The current deactivated with a time constant of ∼60 ms. The amplitude of the peak response to a brief pulse of a saturating concentration of ATP was ∼70% of that obtained during a long application of the same concentration of ATP. Thus, ATP leaves fully liganded channels without producing an opening at least 30% of the time. Extensive kinetic modeling revealed three different schemes that fit the data well, a sequential model and two allosteric models. To account for the delay in opening at saturating ATP, it was necessary to incorporate an intermediate closed state into all three schemes. These kinetic properties indicate that responses to ATP at synapses that use homomeric P2X2 receptors would be expected to greatly outlast the duration of the synaptic ATP transient produced by a single presynaptic spike. Like NMDA receptors, P2X2 receptors provide the potential for complex patterns of synaptic integration over a time scale of hundreds of milliseconds. © The Rockefeller University Press. |
| format |
JOUR |
| author |
Moffatt, L. Hume, R.I. |
| author_facet |
Moffatt, L. Hume, R.I. |
| author_sort |
Moffatt, L. |
| title |
Responses of rat P2X2 receptors to ultrashort pulses of ATP provide insights into ATP binding and channel gating |
| title_short |
Responses of rat P2X2 receptors to ultrashort pulses of ATP provide insights into ATP binding and channel gating |
| title_full |
Responses of rat P2X2 receptors to ultrashort pulses of ATP provide insights into ATP binding and channel gating |
| title_fullStr |
Responses of rat P2X2 receptors to ultrashort pulses of ATP provide insights into ATP binding and channel gating |
| title_full_unstemmed |
Responses of rat P2X2 receptors to ultrashort pulses of ATP provide insights into ATP binding and channel gating |
| title_sort |
responses of rat p2x2 receptors to ultrashort pulses of atp provide insights into atp binding and channel gating |
| url |
http://hdl.handle.net/20.500.12110/paper_00221295_v130_n2_p183_Moffatt |
| work_keys_str_mv |
AT moffattl responsesofratp2x2receptorstoultrashortpulsesofatpprovideinsightsintoatpbindingandchannelgating AT humeri responsesofratp2x2receptorstoultrashortpulsesofatpprovideinsightsintoatpbindingandchannelgating |
| _version_ |
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