Inward and outward currents of native and cloned K(ATP) channels (Kir6.2/SUR1) share single-channel kinetic properties
Background: The ATP-sensitive K+ (K(ATP)) channel is found in a variety of tissues extending from the heart and vascular smooth muscles to the endocrine pancreas and brain. Common to all K(ATP) channels is the pore-forming subunit Kir6.x, a member of the family of small inwardly rectifying K+ channe...
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| Format: | Article |
| Language: | English |
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Elsevier
2022-07-01
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| Series: | Biochemistry and Biophysics Reports |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2405580822000607 |
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| author | Robert Bränström Erik Berglund Robin Fröbom Ingo B. Leibiger Barbara Leibiger Craig A. Aspinwall Olof Larsson Per-Olof Berggren |
| author_facet | Robert Bränström Erik Berglund Robin Fröbom Ingo B. Leibiger Barbara Leibiger Craig A. Aspinwall Olof Larsson Per-Olof Berggren |
| author_sort | Robert Bränström |
| collection | DOAJ |
| description | Background: The ATP-sensitive K+ (K(ATP)) channel is found in a variety of tissues extending from the heart and vascular smooth muscles to the endocrine pancreas and brain. Common to all K(ATP) channels is the pore-forming subunit Kir6.x, a member of the family of small inwardly rectifying K+ channels, and the regulatory subunit sulfonylurea receptor (SURx). In insulin secreting β-cells in the endocrine part of the pancreas, where the channel is best studied, the K(ATP) channel consists of Kir6.2 and SUR1. Under physiological conditions, the K(ATP) channel current flow is outward at membrane potentials more positive than the K+ equilibrium potential around −80 mV. However, K(ATP) channel kinetics have been extensively investigated for inward currents and the single-channel kinetic model is based on this type of recording, whereas only a limited amount of work has focused on outward current kinetics. Methods: We have estimated the kinetic properties of both native and cloned K(ATP) channels under varying ionic gradients and membrane potentials using the patch-clamp technique. Results: Analyses of outward currents in K(ATP) and cloned Kir6.2ΔC26 channels, alone or co-expressed with SUR1, show openings that are not grouped in bursts as seen for inward currents. Burst duration for inward current corresponds well to open time for outward current. Conclusions: Outward K(ATP) channel currents are not grouped in bursts regardless of membrane potential, and channel open time for outward currents corresponds to burst duration for inward currents. |
| first_indexed | 2024-04-13T22:14:15Z |
| format | Article |
| id | doaj.art-04ad32cb51f140e8ac20d35b11721ce8 |
| institution | Directory Open Access Journal |
| issn | 2405-5808 |
| language | English |
| last_indexed | 2024-04-13T22:14:15Z |
| publishDate | 2022-07-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Biochemistry and Biophysics Reports |
| spelling | doaj.art-04ad32cb51f140e8ac20d35b11721ce82022-12-22T02:27:35ZengElsevierBiochemistry and Biophysics Reports2405-58082022-07-0130101260Inward and outward currents of native and cloned K(ATP) channels (Kir6.2/SUR1) share single-channel kinetic propertiesRobert Bränström0Erik Berglund1Robin Fröbom2Ingo B. Leibiger3Barbara Leibiger4Craig A. Aspinwall5Olof Larsson6Per-Olof Berggren7The Rolf Luft Research Center for Diabetes and Endocrinology, Sweden; Endocrine and Sarcoma Surgery Unit, Department of Molecular Medicine and Surgery, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden; Corresponding author. Endocrine and Sarcoma Surgery Unit, Department of Molecular Medicine and Surgery, Karolinska Institutet, SE-171 76, Stockholm, Sweden.Endocrine and Sarcoma Surgery Unit, Department of Molecular Medicine and Surgery, Karolinska Institutet, Karolinska University Hospital, Stockholm, SwedenEndocrine and Sarcoma Surgery Unit, Department of Molecular Medicine and Surgery, Karolinska Institutet, Karolinska University Hospital, Stockholm, SwedenThe Rolf Luft Research Center for Diabetes and Endocrinology, SwedenThe Rolf Luft Research Center for Diabetes and Endocrinology, SwedenDepartment of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, USAThe Rolf Luft Research Center for Diabetes and Endocrinology, SwedenThe Rolf Luft Research Center for Diabetes and Endocrinology, SwedenBackground: The ATP-sensitive K+ (K(ATP)) channel is found in a variety of tissues extending from the heart and vascular smooth muscles to the endocrine pancreas and brain. Common to all K(ATP) channels is the pore-forming subunit Kir6.x, a member of the family of small inwardly rectifying K+ channels, and the regulatory subunit sulfonylurea receptor (SURx). In insulin secreting β-cells in the endocrine part of the pancreas, where the channel is best studied, the K(ATP) channel consists of Kir6.2 and SUR1. Under physiological conditions, the K(ATP) channel current flow is outward at membrane potentials more positive than the K+ equilibrium potential around −80 mV. However, K(ATP) channel kinetics have been extensively investigated for inward currents and the single-channel kinetic model is based on this type of recording, whereas only a limited amount of work has focused on outward current kinetics. Methods: We have estimated the kinetic properties of both native and cloned K(ATP) channels under varying ionic gradients and membrane potentials using the patch-clamp technique. Results: Analyses of outward currents in K(ATP) and cloned Kir6.2ΔC26 channels, alone or co-expressed with SUR1, show openings that are not grouped in bursts as seen for inward currents. Burst duration for inward current corresponds well to open time for outward current. Conclusions: Outward K(ATP) channel currents are not grouped in bursts regardless of membrane potential, and channel open time for outward currents corresponds to burst duration for inward currents.http://www.sciencedirect.com/science/article/pii/S2405580822000607ATP-sensitive K+ (K(ATP)) channelβ-cellsSingle channel kinetics |
| spellingShingle | Robert Bränström Erik Berglund Robin Fröbom Ingo B. Leibiger Barbara Leibiger Craig A. Aspinwall Olof Larsson Per-Olof Berggren Inward and outward currents of native and cloned K(ATP) channels (Kir6.2/SUR1) share single-channel kinetic properties Biochemistry and Biophysics Reports ATP-sensitive K+ (K(ATP)) channel β-cells Single channel kinetics |
| title | Inward and outward currents of native and cloned K(ATP) channels (Kir6.2/SUR1) share single-channel kinetic properties |
| title_full | Inward and outward currents of native and cloned K(ATP) channels (Kir6.2/SUR1) share single-channel kinetic properties |
| title_fullStr | Inward and outward currents of native and cloned K(ATP) channels (Kir6.2/SUR1) share single-channel kinetic properties |
| title_full_unstemmed | Inward and outward currents of native and cloned K(ATP) channels (Kir6.2/SUR1) share single-channel kinetic properties |
| title_short | Inward and outward currents of native and cloned K(ATP) channels (Kir6.2/SUR1) share single-channel kinetic properties |
| title_sort | inward and outward currents of native and cloned k atp channels kir6 2 sur1 share single channel kinetic properties |
| topic | ATP-sensitive K+ (K(ATP)) channel β-cells Single channel kinetics |
| url | http://www.sciencedirect.com/science/article/pii/S2405580822000607 |
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