The Experts below are selected from a list of 276 Experts worldwide ranked by ideXlab platform
John P. Adelman - One of the best experts on this subject based on the ideXlab platform.
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Gene structure and chromosome mapping of the human small-conductance Calcium-Activated Potassium Channel SK1 gene (KCNN1).
Cytogenetic and Genome Research, 1999Co-Authors: Michael Litt, Chris T. Bond, Dante M. Lamorticella, John P. AdelmanAbstract:Abstract. Small-conductance, Calcium-Activated Potassium Channels contribute to the afterhyperpolarization in central neurons and other cell types. Because these Channels regulate neurona
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A human intermediate conductance Calcium-Activated Potassium Channel
Proceedings of the National Academy of Sciences of the United States of America, 1997Co-Authors: Takahiro M. Ishii, Christopher P. Silvia, Birgit Hirschberg, Chris T. Bond, John P. Adelman, James MaylieAbstract:An intermediate conductance Calcium-Activated Potassium Channel, hIK1, was cloned from human pancreas. The predicted amino acid sequence is related to, but distinct from, the small conductance Calcium-Activated Potassium Channel subfamily, which is ≈50% conserved. hIK1 mRNA was detected in peripheral tissues but not in brain. Expression of hIK1 in Xenopus oocytes gave rise to inwardly rectifying Potassium currents, which were activated by submicromolar concentrations of intracellular calcium (K0.5 = 0.3 μM). Although the K0.5 for calcium was similar to that of small conductance Calcium-Activated Potassium Channels, the slope factor derived from the Hill equation was significantly reduced (1.7 vs. 3.5). Single-Channel current amplitudes reflected the macroscopic inward rectification and revealed a conductance level of 39 pS in the inward direction. hIK1 currents were reversibly blocked by charybdotoxin (Ki = 2.5 nM) and clotrimazole (Ki = 24.8 nM) but were minimally affected by apamin (100 nM), iberiotoxin (50 nM), or ketoconazole (10 μM). These biophysical and pharmacological properties are consistent with native intermediate conductance Calcium-Activated Potassium Channels, including the erythrocyte Gardos Channel.
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determinants of apamin and d tubocurarine block in sk Potassium Channels
Journal of Biological Chemistry, 1997Co-Authors: Takahiro M. Ishii, James Maylie, John P. AdelmanAbstract:Abstract Small conductance Calcium-Activated Potassium Channels show a distinct pharmacology. Some, but not all, are blocked by the peptide toxin apamin, and apamin-sensitive Channels are also blocked by d-tubocurarine. Cloned SK Channels (small conductance Calcium-Activated Potassium Channel) recapitulate these properties. We have investigated the structural basis for these differences and found that two amino acid residues on either side of the deep pore are the primary determinants of sensitivity to apamin and differential block by d-tubocurarine. Therefore, the pharmacology of SK Channels compared with other Potassium Channels correlates with structural differences in the outer pore region. However, introduction of a tyrosine residue in the position analogous to that which determines sensitivity to external tetraethylammonium for voltage-gated Potassium Channels endows SK Channels with an equivalent tetraethylammonium sensitivity, indicating that the outer vestibules of the pores are similar. The pharmacology of Channels formed in oocytes coinjected with SK1 and SK2 mRNAs, or with SK1-SK2 dimer mRNA, show that SK subunits may form heteromeric Channels.
Wieslawa Jarmuszkiewicz - One of the best experts on this subject based on the ideXlab platform.
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A large-conductance Calcium-Activated Potassium Channel in potato tuber mitochondria
Biochemical Journal, 2009Co-Authors: Izabela Koszela-piotrowska, Karolina Matkovic, Adam Szewczyk, Wieslawa JarmuszkiewiczAbstract:In the present study, we describe the existence of a novel Potassium Channel in the plant (potato tuber) mitochondrial inner membrane. We found that substances known to modulate large-conductance Calcium-Activated Potassium Channel activity influenced the bioenergetics of potato tuber mitochondria. In isolated mitochondria, Ca2+ and NS1619 (a Potassium Channel opener) were found to depolarize the mitochondrial membrane potential and to stimulate resting respiration. These effects were blocked by iberiotoxin (a Potassium Channel inhibitor) in a Potassium-dependent manner. Additionally, the electrophysiological properties of the large-conductance Potassium Channel present in the potato tuber inner mitochondrial membrane are described in a reconstituted system, using planar lipid bilayers. After incorporation in 50/450 mM KCl gradient solutions, we recorded large-conductance Potassium Channel activity with conductance from 502 ± 15 to 615 ± 12 pS. The probability of Channel opening was increased by Ca2+ and reduced by iberiotoxin. Immunological analysis with antibodies raised against the mammalian plasma membrane large-conductance Ca2+-dependent K+ Channel identified a pore-forming α subunit and an auxiliary β2 subunit of the Channel in potato tuber mitochondrial inner membrane. These results suggest that a large-conductance Calcium-Activated Potassium Channel similar to that of mammalian mitochondria is present in potato tuber mitochondria.
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A large-conductance Calcium-Activated Potassium Channel in potato (Solanum tuberosum) tuber mitochondria.
Biochemical Journal, 2009Co-Authors: Izabela Koszela-piotrowska, Karolina Matkovic, Adam Szewczyk, Wieslawa JarmuszkiewiczAbstract:: In the present study, we describe the existence of a novel Potassium Channel in the plant [potato (Solanum tuberosum) tuber] mitochondrial inner membrane. We found that substances known to modulate large-conductance Calcium-Activated Potassium Channel activity influenced the bioenergetics of potato tuber mitochondria. In isolated mitochondria, Ca2+ and NS1619 {1,3-dihydro-1-[2-hydroxy-5-(trifluoromethyl)phenyl]-5-(trifluoromethyl)-2H-ben-zimidazole-2-one; a Potassium Channel opener} were found to depolarize the mitochondrial membrane potential and to stimulate resting respiration. These effects were blocked by iberiotoxin (a Potassium Channel inhibitor) in a Potassium-dependent manner. Additionally, the electrophysiological properties of the large-conductance Potassium Channel present in the potato tuber inner mitochondrial membrane are described in a reconstituted system, using planar lipid bilayers. After incorporation in 50/450 mM KCl gradient solutions, we recorded large-conductance Potassium Channel activity with conductance from 502+/-15 to 615+/-12 pS. The probability of Channel opening was increased by Ca2+ and reduced by iberiotoxin. Immunological analysis with antibodies raised against the mammalian plasma-membrane large-conductance Ca2+-dependent K+ Channel identified a pore-forming alpha subunit and an auxiliary beta2 subunit of the Channel in potato tuber mitochondrial inner membrane. These results suggest that a large-conductance Calcium-Activated Potassium Channel similar to that of mammalian mitochondria is present in potato tuber mitochondria.
A Schaefer - One of the best experts on this subject based on the ideXlab platform.
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Polymorphisms in the fetal progesterone receptor and a Calcium-Activated Potassium Channel isoform are associated with preterm birth in an Argentinian population
Journal of Perinatology, 2013Co-Authors: P C Mann, Margaret E. Cooper, Kelli K. Ryckman, Belén Comas, Juan Antonio Gili, S Crumley, Elise N.a. Bream, Heather M. Byers, Travis L. Piester, A SchaeferAbstract:Objective: To investigate genetic etiologies of preterm birth (PTB) in Argentina through evaluation of single-nucleotide polymorphisms (SNPs) in candidate genes and population genetic admixture. Study Design: Genotyping was performed in 389 families. Maternal, paternal and fetal effects were studied separately. Mitochondrial DNA (mtDNA) was sequenced in 50 males and 50 females. Y-chromosome anthropological markers were evaluated in 50 males. Result: Fetal association with PTB was found in the progesterone receptor ( PGR , rs1942836; P =0.004). Maternal association with PTB was found in small conductance calcium activated Potassium Channel isoform 3 ( KCNN3 , rs883319; P =0.01). Gestational age associated with PTB in PGR rs1942836 at 32–36 weeks ( P =0.0004). MtDNA sequencing determined 88 individuals had Amerindian consistent haplogroups. Two individuals had Amerindian Y-chromosome consistent haplotypes. Conclusion: This study replicates single locus fetal associations with PTB in PGR , maternal association in KCNN3 , and demonstrates possible effects for divergent racial admixture on PTB.
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Polymorphisms in the fetal progesterone receptor and a Calcium-Activated Potassium Channel isoform are associated with preterm birth in an Argentinian population
Journal of Perinatology, 2012Co-Authors: P C Mann, Margaret E. Cooper, Kelli K. Ryckman, Belén Comas, Juan Antonio Gili, S Crumley, Elise N.a. Bream, Heather M. Byers, Travis L. Piester, A SchaeferAbstract:Polymorphisms in the fetal progesterone receptor and a Calcium-Activated Potassium Channel isoform are associated with preterm birth in an Argentinian population
A Germana - One of the best experts on this subject based on the ideXlab platform.
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calcium activated Potassium Channel sk1 is widely expressed in the peripheral nervous system and sensory organs of adult zebrafish
Neuroscience Letters, 2013Co-Authors: R Cabo, Rosalia Zichichi, E Vina, M C Guerrera, G Vazquez, Olivia Garciasuarez, J A Vega, A GermanaAbstract:Abstract Sensory cells contain ion Channels involved in the organ-specific transduction mechanisms that convert different types of stimuli into electric energy. Here we focus on small-conductance Calcium-Activated Potassium Channel 1 (SK1) which plays an important role in all excitable cells acting as feedback regulators in after-hyperpolarization. This study was undertaken to analyze the pattern of expression of SK1 in the zebrafish peripheral nervous system and sensory organs using RT-PRC, Westernblot and immunohistochemistry. Expression of SK1 mRNA was observed at all developmental stages analyzed (from 10 to 100 days post fertilization, dpf), and the antibody used identified a protein with a molecular weight of 70 kDa, at 100 dpf (regarded to be adult). Cell expressing SK1 in adult animals were neurons of dorsal root and cranial nerve sensory ganglia, sympathetic neurons, sensory cells in neuromasts of the lateral line system and taste buds, crypt olfactory neurons and photoreceptors. Present results report for the first time the expression and the distribution of SK1 in the peripheral nervous system and sensory organs of adult zebrafish, and may contribute to set zebrafish as an interesting experimental model for Calcium-Activated Potassium Channels research. Moreover these findings are of potential interest because the potential role of SK as targets for the treatment of neurological diseases and sensory disorders.
Adam Szewczyk - One of the best experts on this subject based on the ideXlab platform.
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Mechanosensitivity of mitochondrial large-conductance Calcium-Activated Potassium Channels.
Biochimica et Biophysica Acta, 2018Co-Authors: Agnieszka Walewska, Adam Szewczyk, Bogusz Kulawiak, Piotr KoprowskiAbstract:Abstract Potassium Channels have been discovered in the inner mitochondrial membrane of various cells. These Channels can regulate the mitochondrial membrane potential, the matrix volume, respiration and reactive species generation. Therefore, it is believed that their activation is cytoprotective in various tissues. In our study, the single-Channel activity of a large-conductance Calcium-Activated Potassium Channel (mitoBKCa) was measured by the patch-clamp technique on mitoplasts derived from mitochondria isolated from human glioma U-87 MG cells. Here, we show for the first time that mechanical stimulation of mitoBKCa Channels results in an increased probability of Channel opening. However, the mechanosensitivity of mitoBKCa Channels was variable with some Channels exhibiting no mechanosensitivity. We detected the expression of mechanosensitive BKCa-STREX exon in U-87 MG cells and hypotesize, based on previous studies demonstrating the presence of multiple BKCa splice variants that variable mechanosensitivity of mitoBKCa could be the result of the presence of diverse BKCa isoforms in mitochondria of U-87 MG cells. Our findings indicate the possible involvement of the mitoBKCa Channel in mitochondria activities in which changes in membrane tension and shape play a crucial role, such as fusion/fission and cristae remodeling.
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A large-conductance Calcium-Activated Potassium Channel in potato tuber mitochondria
Biochemical Journal, 2009Co-Authors: Izabela Koszela-piotrowska, Karolina Matkovic, Adam Szewczyk, Wieslawa JarmuszkiewiczAbstract:In the present study, we describe the existence of a novel Potassium Channel in the plant (potato tuber) mitochondrial inner membrane. We found that substances known to modulate large-conductance Calcium-Activated Potassium Channel activity influenced the bioenergetics of potato tuber mitochondria. In isolated mitochondria, Ca2+ and NS1619 (a Potassium Channel opener) were found to depolarize the mitochondrial membrane potential and to stimulate resting respiration. These effects were blocked by iberiotoxin (a Potassium Channel inhibitor) in a Potassium-dependent manner. Additionally, the electrophysiological properties of the large-conductance Potassium Channel present in the potato tuber inner mitochondrial membrane are described in a reconstituted system, using planar lipid bilayers. After incorporation in 50/450 mM KCl gradient solutions, we recorded large-conductance Potassium Channel activity with conductance from 502 ± 15 to 615 ± 12 pS. The probability of Channel opening was increased by Ca2+ and reduced by iberiotoxin. Immunological analysis with antibodies raised against the mammalian plasma membrane large-conductance Ca2+-dependent K+ Channel identified a pore-forming α subunit and an auxiliary β2 subunit of the Channel in potato tuber mitochondrial inner membrane. These results suggest that a large-conductance Calcium-Activated Potassium Channel similar to that of mammalian mitochondria is present in potato tuber mitochondria.
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A large-conductance Calcium-Activated Potassium Channel in potato (Solanum tuberosum) tuber mitochondria.
Biochemical Journal, 2009Co-Authors: Izabela Koszela-piotrowska, Karolina Matkovic, Adam Szewczyk, Wieslawa JarmuszkiewiczAbstract:: In the present study, we describe the existence of a novel Potassium Channel in the plant [potato (Solanum tuberosum) tuber] mitochondrial inner membrane. We found that substances known to modulate large-conductance Calcium-Activated Potassium Channel activity influenced the bioenergetics of potato tuber mitochondria. In isolated mitochondria, Ca2+ and NS1619 {1,3-dihydro-1-[2-hydroxy-5-(trifluoromethyl)phenyl]-5-(trifluoromethyl)-2H-ben-zimidazole-2-one; a Potassium Channel opener} were found to depolarize the mitochondrial membrane potential and to stimulate resting respiration. These effects were blocked by iberiotoxin (a Potassium Channel inhibitor) in a Potassium-dependent manner. Additionally, the electrophysiological properties of the large-conductance Potassium Channel present in the potato tuber inner mitochondrial membrane are described in a reconstituted system, using planar lipid bilayers. After incorporation in 50/450 mM KCl gradient solutions, we recorded large-conductance Potassium Channel activity with conductance from 502+/-15 to 615+/-12 pS. The probability of Channel opening was increased by Ca2+ and reduced by iberiotoxin. Immunological analysis with antibodies raised against the mammalian plasma-membrane large-conductance Ca2+-dependent K+ Channel identified a pore-forming alpha subunit and an auxiliary beta2 subunit of the Channel in potato tuber mitochondrial inner membrane. These results suggest that a large-conductance Calcium-Activated Potassium Channel similar to that of mammalian mitochondria is present in potato tuber mitochondria.
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Large-conductance Calcium-Activated Potassium Channel In Neuronal Mitochondria
Biophysical Journal, 2009Co-Authors: Adam Szewczyk, Marta Piwońska, Piotr Bednarczyk, Krzysztof DołowyAbstract:Large-conductance Calcium-Activated Potassium (BK) Channels are expressed in the plasma membrane of various cell types. Interestingly, recent studies provide evidence for existence of this Channel also in mitochondria. The goal of the present study was to find a candidate for the regulatory component of the large conductance calcium activated Potassium Channel in neurons. A combined approach of western blot analysis, high-resolution immunofluorescence and immunoelectron microscopy with the use of antibodies directed against four distinct beta subunits demonstrated the presence of the BK Channel beta4 subunit in the inner membrane of neuronal mitochondria in rat brain and cultured neurons. Additionally, Channel activity was measured with the use of patch-clamp technique.The study was supported by grant from Ministry of Science and Higher Education No P-N/031/2006 and Polish Mitochondrial Network MitoNet.pl.
