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Chiang WT, Chang YK, Hui WH, Chang SW, Liao CY, Chang YC, Chen CJ, Wang WC, Lai CC, Wang CH, Luo SY, Huang YP, Chou SH, Horng TL, Hou MH, Muench SP, Chen RS, Tsai MD, Hu NJ. Structural basis and synergism of ATP and Na + activation in bacterial K + uptake system KtrAB. Nat Commun 2024; 15:3850. [PMID: 38719864 PMCID: PMC11078986 DOI: 10.1038/s41467-024-48057-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Accepted: 04/17/2024] [Indexed: 05/12/2024] Open
Abstract
The K+ uptake system KtrAB is essential for bacterial survival in low K+ environments. The activity of KtrAB is regulated by nucleotides and Na+. Previous studies proposed a putative gating mechanism of KtrB regulated by KtrA upon binding to ATP or ADP. However, how Na+ activates KtrAB and the Na+ binding site remain unknown. Here we present the cryo-EM structures of ATP- and ADP-bound KtrAB from Bacillus subtilis (BsKtrAB) both solved at 2.8 Å. A cryo-EM density at the intra-dimer interface of ATP-KtrA was identified as Na+, as supported by X-ray crystallography and ICP-MS. Thermostability assays and functional studies demonstrated that Na+ binding stabilizes the ATP-bound BsKtrAB complex and enhances its K+ flux activity. Comparing ATP- and ADP-BsKtrAB structures suggests that BsKtrB Arg417 and Phe91 serve as a channel gate. The synergism of ATP and Na+ in activating BsKtrAB is likely applicable to Na+-activated K+ channels in central nervous system.
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Affiliation(s)
- Wesley Tien Chiang
- Graduate Institute of Biochemistry, National Chung Hsing University, Taichung, 402202, Taiwan
| | - Yao-Kai Chang
- Institute of Biological Chemistry, Academia Sinica, Taipei, 115201, Taiwan
| | - Wei-Han Hui
- Department of Civil Engineering, National Taiwan University, Taipei, 106319, Taiwan
| | - Shu-Wei Chang
- Department of Civil Engineering, National Taiwan University, Taipei, 106319, Taiwan
- Department of Biomedical Engineering, National Taiwan University, Taipei, 10663, Taiwan
| | - Chen-Yi Liao
- Graduate Institute of Biochemistry, National Chung Hsing University, Taichung, 402202, Taiwan
| | - Yi-Chuan Chang
- Graduate Institute of Biochemistry, National Chung Hsing University, Taichung, 402202, Taiwan
| | - Chun-Jung Chen
- Life Science Group, Scientific Research Division, National Synchrotron Radiation Research Center, Hsinchu, 30092, Taiwan
| | - Wei-Chen Wang
- Institute of Molecular Biology, National Chung Hsing University, Taichung, 402202, Taiwan
| | - Chien-Chen Lai
- Institute of Molecular Biology, National Chung Hsing University, Taichung, 402202, Taiwan
- Graduate Institute of Chinese Medical Science, China Medical University, Taichung, 406040, Taiwan
| | - Chun-Hsiung Wang
- Institute of Biological Chemistry, Academia Sinica, Taipei, 115201, Taiwan
| | - Siou-Ying Luo
- Institute of Biological Chemistry, Academia Sinica, Taipei, 115201, Taiwan
| | - Ya-Ping Huang
- Institute of Biological Chemistry, Academia Sinica, Taipei, 115201, Taiwan
| | - Shan-Ho Chou
- Graduate Institute of Biochemistry, National Chung Hsing University, Taichung, 402202, Taiwan
| | - Tzyy-Leng Horng
- Department of Applied Mathematics, Feng Chia University, Taichung, 407102, Taiwan
| | - Ming-Hon Hou
- Institute of Genomics and Bioinformatics, National Chung Hsing University, Taichung, 402202, Taiwan
| | - Stephen P Muench
- School of Biomedical Sciences, Faculty of Biological Sciences and the Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Ren-Shiang Chen
- Department of Life Science, Tunghai University, Taichung, 407224, Taiwan
| | - Ming-Daw Tsai
- Institute of Biological Chemistry, Academia Sinica, Taipei, 115201, Taiwan.
- Institute of Biochemical Sciences, National Taiwan University, Taipei, 106319, Taiwan.
| | - Nien-Jen Hu
- Graduate Institute of Biochemistry, National Chung Hsing University, Taichung, 402202, Taiwan.
- Ph.D Program in Translational Medicine, National Chung Hsing University, Taichung, 402202, Taiwan.
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He W, Su Y, Peng HB, Tong P. Dynamic heterogeneity and non-Gaussian statistics for ganglioside GM1s and acetylcholine receptors on live cell membrane. Mol Biol Cell 2020; 31:1380-1391. [PMID: 32348189 PMCID: PMC7353135 DOI: 10.1091/mbc.e19-08-0473] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
We have carried out a comparative study of the lateral motion of ganglioside GM1, which is a glycosphingolipid residing on the outer leaflet of the plasma membrane, and acetylcholine receptor (AChR), which is a well-characterized ion channel. Both the lipid molecules and the transmembrane proteins reside on the plasma membranes of live Xenopus muscle cells. From a thorough analysis of a large volume of individual molecular trajectories obtained from more than 300 live cells over a wide range of sampling rates and long durations, we find that the GM1s and AChRs share the same dynamic heterogeneity and non-Gaussian statistics. Our measurements with the ATP-depleted cells reveal that the diffusion dynamics of the GM1s and AChRs is uniformly affected by the intracellular ATP level of the living muscle cells, further demonstrating that membrane diffusion is strongly coupled to the dynamics of the underlying cortical actin network, as predicted by the dynamic picket-fence model.
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Affiliation(s)
- Wei He
- Nano Science and Technology Program, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - Yun Su
- Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - H Benjamin Peng
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - Penger Tong
- Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
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Mao X, Bruneau N, Gao Q, Becq H, Jia Z, Xi H, Shu L, Wang H, Szepetowski P, Aniksztejn L. The Epilepsy of Infancy With Migrating Focal Seizures: Identification of de novo Mutations of the KCNT2 Gene That Exert Inhibitory Effects on the Corresponding Heteromeric K Na1.1/K Na1.2 Potassium Channel. Front Cell Neurosci 2020; 14:1. [PMID: 32038177 PMCID: PMC6992647 DOI: 10.3389/fncel.2020.00001] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Accepted: 01/06/2020] [Indexed: 12/21/2022] Open
Abstract
The epilepsy of infancy with migrating focal seizures (EIMFS; previously called Malignant migrating partial seizures of infancy) are early-onset epileptic encephalopathies (EOEE) that associate multifocal ictal discharges and profound psychomotor retardation. EIMFS have a genetic origin and are mostly caused by de novo mutations in the KCNT1 gene, and much more rarely in the KCNT2 gene. KCNT1 and KCNT2 respectively encode the KNa1.1 (Slack) and KNa1.2 (Slick) subunits of the sodium-dependent voltage-gated potassium channel KNa. Functional analyses of the corresponding mutant homomeric channels in vitro suggested gain-of-function effects. Here, we report two novel, de novo truncating mutations of KCNT2: one mutation is frameshift (p.L48Qfs43), is situated in the N-terminal domain, and was found in a patient with EOEE (possibly EIMFS); the other mutation is nonsense (p.K564*), is located in the C-terminal region, and was found in a typical EIMFS patient. Using whole-cell patch-clamp recordings, we have analyzed the functional consequences of those two novel KCNT2 mutations on reconstituted KNa1.2 homomeric and KNa1.1/KNa1.2 heteromeric channels in transfected chinese hamster ovary (CHO) cells. We report that both mutations significantly impacted on KNa function; notably, they decreased the global current density of heteromeric channels by ~25% (p.K564*) and ~55% (p.L48Qfs43). Overall our data emphasize the involvement of KCNT2 in EOEE and provide novel insights into the role of heteromeric KNa channel in the severe KCNT2-related epileptic phenotypes. This may have important implications regarding the elaboration of future treatment.
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Affiliation(s)
- Xiao Mao
- Hunan Provincial Maternal and Child Health Care Hospital, Changsha, China
- NHC Key Laboratory of Birth Defects Research, Prevention and Treatment, Changsha, China
| | - Nadine Bruneau
- INSERM, Aix-Marseille University, INMED, UMR1249, Marseille, France
| | - Quwen Gao
- Department of Epilepsy, General Hospital of Southern Theater Command, Guangzhou, China
| | - Hélène Becq
- INSERM, Aix-Marseille University, INMED, UMR1249, Marseille, France
| | - Zhengjun Jia
- Hunan Provincial Maternal and Child Health Care Hospital, Changsha, China
- NHC Key Laboratory of Birth Defects Research, Prevention and Treatment, Changsha, China
| | - Hui Xi
- Hunan Provincial Maternal and Child Health Care Hospital, Changsha, China
- NHC Key Laboratory of Birth Defects Research, Prevention and Treatment, Changsha, China
| | - Li Shu
- Hunan Provincial Maternal and Child Health Care Hospital, Changsha, China
- NHC Key Laboratory of Birth Defects Research, Prevention and Treatment, Changsha, China
| | - Hua Wang
- Hunan Provincial Maternal and Child Health Care Hospital, Changsha, China
- NHC Key Laboratory of Birth Defects Research, Prevention and Treatment, Changsha, China
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4
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The Slo(w) path to identifying the mitochondrial channels responsible for ischemic protection. Biochem J 2017; 474:2067-2094. [PMID: 28600454 DOI: 10.1042/bcj20160623] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Revised: 02/10/2017] [Accepted: 02/13/2017] [Indexed: 12/19/2022]
Abstract
Mitochondria play an important role in tissue ischemia and reperfusion (IR) injury, with energetic failure and the opening of the mitochondrial permeability transition pore being the major causes of IR-induced cell death. Thus, mitochondria are an appropriate focus for strategies to protect against IR injury. Two widely studied paradigms of IR protection, particularly in the field of cardiac IR, are ischemic preconditioning (IPC) and volatile anesthetic preconditioning (APC). While the molecular mechanisms recruited by these protective paradigms are not fully elucidated, a commonality is the involvement of mitochondrial K+ channel opening. In the case of IPC, research has focused on a mitochondrial ATP-sensitive K+ channel (mitoKATP), but, despite recent progress, the molecular identity of this channel remains a subject of contention. In the case of APC, early research suggested the existence of a mitochondrial large-conductance K+ (BK, big conductance of potassium) channel encoded by the Kcnma1 gene, although more recent work has shown that the channel that underlies APC is in fact encoded by Kcnt2 In this review, we discuss both the pharmacologic and genetic evidence for the existence and identity of mitochondrial K+ channels, and the role of these channels both in IR protection and in regulating normal mitochondrial function.
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Kaczmarek LK, Aldrich RW, Chandy KG, Grissmer S, Wei AD, Wulff H. International Union of Basic and Clinical Pharmacology. C. Nomenclature and Properties of Calcium-Activated and Sodium-Activated Potassium Channels. Pharmacol Rev 2017; 69:1-11. [PMID: 28267675 PMCID: PMC11060434 DOI: 10.1124/pr.116.012864] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2024] Open
Abstract
A subset of potassium channels is regulated primarily by changes in the cytoplasmic concentration of ions, including calcium, sodium, chloride, and protons. The eight members of this subfamily were originally all designated as calcium-activated channels. More recent studies have clarified the gating mechanisms for these channels and have documented that not all members are sensitive to calcium. This article describes the molecular relationships between these channels and provides an introduction to their functional properties. It also introduces a new nomenclature that differentiates between calcium- and sodium-activated potassium channels.
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Affiliation(s)
- Leonard K Kaczmarek
- Departments of Pharmacology and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut (L.K.K.); Center for Learning and Memory and Department of Neuroscience, University of Texas at Austin, Austin, Texas (R.W.A.); Laboratory of Molecular Physiology in the Infection and Immunity Theme, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore (K.G.C.); Institute of Applied Physiology, Ulm University, Ulm, Germany (S.G.); Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington (A.D.W.); and Department of Pharmacology, School of Medicine, University of California, Davis, California (H.W.)
| | - Richard W Aldrich
- Departments of Pharmacology and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut (L.K.K.); Center for Learning and Memory and Department of Neuroscience, University of Texas at Austin, Austin, Texas (R.W.A.); Laboratory of Molecular Physiology in the Infection and Immunity Theme, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore (K.G.C.); Institute of Applied Physiology, Ulm University, Ulm, Germany (S.G.); Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington (A.D.W.); and Department of Pharmacology, School of Medicine, University of California, Davis, California (H.W.)
| | - K George Chandy
- Departments of Pharmacology and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut (L.K.K.); Center for Learning and Memory and Department of Neuroscience, University of Texas at Austin, Austin, Texas (R.W.A.); Laboratory of Molecular Physiology in the Infection and Immunity Theme, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore (K.G.C.); Institute of Applied Physiology, Ulm University, Ulm, Germany (S.G.); Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington (A.D.W.); and Department of Pharmacology, School of Medicine, University of California, Davis, California (H.W.)
| | - Stephan Grissmer
- Departments of Pharmacology and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut (L.K.K.); Center for Learning and Memory and Department of Neuroscience, University of Texas at Austin, Austin, Texas (R.W.A.); Laboratory of Molecular Physiology in the Infection and Immunity Theme, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore (K.G.C.); Institute of Applied Physiology, Ulm University, Ulm, Germany (S.G.); Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington (A.D.W.); and Department of Pharmacology, School of Medicine, University of California, Davis, California (H.W.)
| | - Aguan D Wei
- Departments of Pharmacology and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut (L.K.K.); Center for Learning and Memory and Department of Neuroscience, University of Texas at Austin, Austin, Texas (R.W.A.); Laboratory of Molecular Physiology in the Infection and Immunity Theme, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore (K.G.C.); Institute of Applied Physiology, Ulm University, Ulm, Germany (S.G.); Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington (A.D.W.); and Department of Pharmacology, School of Medicine, University of California, Davis, California (H.W.)
| | - Heike Wulff
- Departments of Pharmacology and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut (L.K.K.); Center for Learning and Memory and Department of Neuroscience, University of Texas at Austin, Austin, Texas (R.W.A.); Laboratory of Molecular Physiology in the Infection and Immunity Theme, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore (K.G.C.); Institute of Applied Physiology, Ulm University, Ulm, Germany (S.G.); Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington (A.D.W.); and Department of Pharmacology, School of Medicine, University of California, Davis, California (H.W.)
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6
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Suzuki T, Hansen A, Sanguinetti MC. Hydrophobic interactions between the S5 segment and the pore helix stabilizes the closed state of Slo2.1 potassium channels. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1858:783-92. [PMID: 26724206 DOI: 10.1016/j.bbamem.2015.12.024] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Revised: 11/26/2015] [Accepted: 12/21/2015] [Indexed: 11/28/2022]
Abstract
Under normal physiological conditions, Slo2.1K(+) channels are in a closed state unless activated by an elevation in [Na(+)]i. Fenamates such as niflumic acid also activate Slo2.1. Previous studies suggest that activation of Slo2.1 channels is mediated by a conformational change in the selectivity filter, and not a widening of the aperture formed by the S6 segment bundle crossing as occurs in voltage-gated K(+) channels. It is unclear how binding of Na(+) or fenamates is allosterically linked to opening of the presumed selectivity filter activation gate in Slo2.1. Here we examined the role of the S5 transmembrane segment in the activation of Slo2.1. Channels were heterologously expressed in Xenopus laevis oocytes and whole cell currents measured with the voltage-clamp technique. Ala substitution of five residues located on a single face of the S5 α-helical segment induced constitutive channel activity. Leu-209, predicted to face towards Phe-240 in the pore helix was investigated by further mutagenesis. Mutation of Leu-209 to Glu or Gln induced maximal channel activation as did the combined mutation to Ala of all three hydrophobic S5 residues predicted to be adjacent to Phe-240. Together these results suggest that hydrophobic interactions between residues in S5 and the C-terminal end of the pore helix stabilize Slo2.1 channels in a closed state.
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Affiliation(s)
- Tomoyuki Suzuki
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT 84112, USA
| | - Angela Hansen
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT 84112, USA
| | - Michael C Sanguinetti
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT 84112, USA; Department of Internal Medicine, Division of Cardiovascular Medicine, University of Utah, Salt Lake City, UT 84112, USA.
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Tomasello DL, Gancarz-Kausch AM, Dietz DM, Bhattacharjee A. Transcriptional Regulation of the Sodium-activated Potassium Channel SLICK (KCNT2) Promoter by Nuclear Factor-κB. J Biol Chem 2015; 290:18575-83. [PMID: 26100633 DOI: 10.1074/jbc.m115.643536] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Indexed: 11/06/2022] Open
Abstract
Although recent studies have shown the sodium-activated potassium channel SLACK (KCNT1) can contribute to neuronal excitability, there remains little information on the physiological role of the closely related SLICK (KCNT2) channel. Activation of SLICK channels may be important during pathological states such as ischemia, in which an increase in intracellular sodium and chloride can perturb membrane potential and ion homeostasis. We have identified two NFκB-binding sites within the promoter region of the human SLICK (KCNT2) and orthologous rat Slick (Kcnt2) genes, suggesting that conditions in which NFκB transcriptional activity is elevated promote expression of this channel. NFκB binding to the rat Slick promoter was confirmed in vivo by ChIP analyses, and NFκB was found differentially bound to the two sites. We verified NFκB transcriptional regulation of SLICK/Slick by mutational analyses and studying gene expression by luciferase assay in P19 cells, where NFκB is constitutively active. For the rat gene, activation of the Slick promoter was found to be additive in single NFκB mutations and synergistic in double mutations. Unexpectedly, for the human gene, NFκB exhibited cooperativity in activating the SLICK promoter. The human SLICK promoter constructs were then tested under hypoxic conditions in PC-12 cells, where NFκB is not active. Only under hypoxic conditions could luciferase activity be detected; the double NFκB mutant construct failed to exhibit activity. Transcriptional regulation of Slick by NFκB was verified in primary neurons. The Slick transcript decreased 24 h after NFκB inhibition. Our data show SLICK expression is predominantly under the control of NFκB. Because neuronal NFκB activation occurs during stressful stimuli such as hypoxia and injury, our findings suggest that SLICK is a neuroprotective gene.
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Affiliation(s)
| | - Amy M Gancarz-Kausch
- Department of Pharmacology and Toxicology, The State University of New York at Buffalo, Buffalo, New York 14214
| | - David M Dietz
- From the Program in Neuroscience and Department of Pharmacology and Toxicology, The State University of New York at Buffalo, Buffalo, New York 14214
| | - Arin Bhattacharjee
- From the Program in Neuroscience and Department of Pharmacology and Toxicology, The State University of New York at Buffalo, Buffalo, New York 14214
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Thomson SJ, Hansen A, Sanguinetti MC. Identification of the Intracellular Na+ Sensor in Slo2.1 Potassium Channels. J Biol Chem 2015; 290:14528-35. [PMID: 25903137 DOI: 10.1074/jbc.m115.653089] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Indexed: 01/14/2023] Open
Abstract
Slo2 potassium channels have a very low open probability under normal physiological conditions, but are readily activated in response to an elevated [Na(+)]i (e.g. during ischemia). An intracellular Na(+) coordination motif (DX(R/K)XXH) was previously identified in Kir3.2, Kir3.4, Kir5.1, and Slo2.2 channel subunits. Based loosely on this sequence, we identified five potential Na(+) coordination motifs in the C terminus of the Slo2.1 subunit. The Asp residue in each sequence was substituted with Arg, and single mutant channels were heterologously expressed in Xenopus oocytes. The Na(+) sensitivity of each of the mutant channels was assessed by voltage clamp of oocytes using micropipettes filled with 2 M NaCl. Wild-type channels and four of the mutant Slo2.1 channels were rapidly activated by leakage of NaCl solution into the cytoplasm. D757R Slo2.1 channels were not activated by NaCl, but were activated by the fenamate niflumic acid, confirming their functional expression. In whole cell voltage clamp recordings of HEK293 cells, wild-type but not D757R Slo2.1 channels were activated by a [NaCl]i of 70 mM. Thus, a single Asp residue can account for the sensitivity of Slo2.1 channels to intracellular Na(+). In excised inside-out macropatches of HEK293 cells, activation of wild-type Slo2.1 currents by 3 mM niflumic acid was 14-fold greater than activation achieved by increasing [NaCl]i from 3 to 100 mM. Thus, relative to fenamates, intracellular Na(+) is a poor activator of Slo2.1.
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Affiliation(s)
- Steven J Thomson
- From the Nora Eccles Harrison Cardiovascular Research and Training Institute and
| | - Angela Hansen
- From the Nora Eccles Harrison Cardiovascular Research and Training Institute and
| | - Michael C Sanguinetti
- From the Nora Eccles Harrison Cardiovascular Research and Training Institute and Department of Internal Medicine, Division of Cardiovascular Medicine, University of Utah, Salt Lake City, Utah 84112
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