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https://www.readbyqxmd.com/read/29705199/determination-of-the-stoichiometry-between-%C3%AE-and-%C3%AE-1-subunits-of-the-bk-channel-using-lret
#1
Willy Carrasquel-Ursulaez, Osvaldo Alvarez, Francisco Bezanilla, Ramon Latorre
Two families of accessory proteins, β and γ, modulate BK channel gating and pharmacology. Notably, in the absence of internal Ca2+ , the γ1 subunit promotes a large shift of the BK conductance-voltage curve to more negative potentials. However, very little is known about how α- and γ1 subunits interact. In particular, the association stoichiometry between both subunits is unknown. Here, we propose a method to answer this question using lanthanide resonance energy transfer. The method assumes that the kinetics of lanthanide resonance energy transfer-sensitized emission of the donor double-labeled α/γ1 complex is the linear combination of the kinetics of the sensitized emission in single-labeled complexes...
April 25, 2018: Biophysical Journal
https://www.readbyqxmd.com/read/29545539/solution-structure-of-extracellular-loop-of-human-%C3%AE-4-subunit-of-bk-channel-and-its-biological-implication-on-chtx-sensitivity
#2
Yanting Wang, Wenxian Lan, Zhenzhen Yan, Jing Gao, Xinlian Liu, Sheng Wang, Xiying Guo, Chunxi Wang, Hu Zhou, Jiuping Ding, Chunyang Cao
Large-conductance Ca2+ - and voltage-dependent K+ (BK) channels display diverse biological functions while their pore-forming α subunit is coded by a single Slo1 gene. The variety of BK channels is correlated with the effects of BKα coexpression with auxiliary β (β1-β4) subunits, as well as newly defined γ subunits. Charybdotoxin (ChTX) blocks BK channel through physically occluding the K+ -conduction pore. Human brain enriched β4 subunit (hβ4) alters the conductance-voltage curve, slows activation and deactivation time courses of BK channels...
March 15, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29466671/lipopolysaccharide-stimulates-bk-channel-activity-in-bladder-umbrella-cells
#3
Ming Lu, Jian-Ri Li, Lery Alvarez-Lugo, Yan Li, Shan Yu, Xuanhao Li, Benkang Shi, Toby C Chai
Bladder urothelium plays an active role in response to bacterial infection. There is little known about the electrophysiological activity in urothelial cells in this process. We used a non-enzymatic method to isolate bladder urothelial tissue and to patch clamp umbrella cells in situ. A 200pS conductance potassium (K+ ) channel was detected from female C57BL6 mice. Of 58 total patches, 17.2% patches displayed the 200pS K+ conductance channel. This K+ conductance channel showed Ca2+ sensitivity and voltage dependence...
February 21, 2018: American Journal of Physiology. Cell Physiology
https://www.readbyqxmd.com/read/29373813/functional-regulation-of-large-conductance-ca-2-activated-k-channels-in-vascular-diseases
#4
REVIEW
Yanrong Zhu, Peng Ye, Shao-Liang Chen, Dai-Min Zhang
The large conductance Ca2+ -activated potassium channels, the BK channels, is widely expressed in various tissues and activated in a Ca2+ - and voltage-dependent manner. The activation of BK channels hyperpolarizes vascular smooth muscle cell membrane potential, resulting in vasodilation. Under pathophysiological conditions, such as diabetes mellitus and hypertension, impaired BK channel function exacerbates vascular vasodilation and leads to organ ischemia. The vascular BK channel is composed of 4 pore-forming subunits, BK-α together with 4 auxiliary subunits: β1 subunits (BK-β1 ) or γ1 subunits (BK-γ1 )...
January 23, 2018: Metabolism: Clinical and Experimental
https://www.readbyqxmd.com/read/29025867/threading-the-biophysics-of-mammalian-slo1-channels-onto-structures-of-an-invertebrate-slo1-channel
#5
REVIEW
Yu Zhou, Huanghe Yang, Jianmin Cui, Christopher J Lingle
For those interested in the machinery of ion channel gating, the Ca2+ and voltage-activated BK K+ channel provides a compelling topic for investigation, by virtue of its dual allosteric regulation by both voltage and intracellular Ca2+ and because its large-single channel conductance facilitates detailed kinetic analysis. Over the years, biophysical analyses have illuminated details of the allosteric regulation of BK channels and revealed insights into the mechanism of BK gating, e.g., inner cavity size and accessibility and voltage sensor-pore coupling...
November 6, 2017: Journal of General Physiology
https://www.readbyqxmd.com/read/28953901/allosteric-activation-mechanism-of-bk-channel-gating-ring-triggered-by-calcium-ions
#6
Ronghua Guan, Hui Zhou, Junwei Li, Shaoying Xiao, Chunli Pang, Yafei Chen, Xiangrong Du, Shaoxi Ke, Qiongyao Tang, Jiguo Su, Yong Zhan, Hailong An
Calcium ions bind at the gating ring which triggers the gating of BK channels. However, the allosteric mechanism by which Ca2+ regulates the gating of BK channels remains obscure. Here, we applied Molecular Dynamics (MD) and Targeted MD to the integrated gating ring of BK channels, and achieved the transition from the closed state to a half-open state. Our date show that the distances of the diagonal subunits increase from 41.0 Å at closed state to 45.7Å or 46.4 Å at a half-open state. It is the rotatory motion and flower-opening like motion of the gating rings which are thought to pull the bundle crossing gate to open ultimately...
2017: PloS One
https://www.readbyqxmd.com/read/28696251/endothelin-1-stimulates-vasoconstriction-through-rab11a-serine-177-phosphorylation
#7
Xue Zhai, M Dennis Leo, Jonathan H Jaggar
RATIONALE: Large-conductance calcium-activated potassium channels (BK) are composed of pore-forming BKα and auxiliary β1 subunits in arterial smooth muscle cells (myocytes). Vasoconstrictors, including endothelin-1 (ET-1), inhibit myocyte BK channels, leading to contraction, but mechanisms involved are unclear. Recent evidence indicates that BKα is primarily plasma membrane localized, whereas the cellular location of β1 can be rapidly altered by Rab11A-positive recycling endosomes...
September 1, 2017: Circulation Research
https://www.readbyqxmd.com/read/28600454/the-slo-w-path-to-identifying-the-mitochondrial-channels-responsible-for-ischemic-protection
#8
REVIEW
Charles Owen Smith, Keith Nehrke, Paul S Brookes
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...
June 9, 2017: Biochemical Journal
https://www.readbyqxmd.com/read/28487419/membrane-depolarization-activates-bk-channels-through-rock-mediated-%C3%AE-1-subunit-surface-trafficking-to-limit-vasoconstriction
#9
M Dennis Leo, Xue Zhai, Padmapriya Muralidharan, Korah P Kuruvilla, Simon Bulley, Frederick A Boop, Jonathan H Jaggar
Membrane depolarization of smooth muscle cells (myocytes) in the small arteries that regulate regional organ blood flow leads to vasoconstriction. Membrane depolarization also activates large-conductance calcium (Ca2+ )-activated potassium (BK) channels, which limits Ca2+ channel activity that promotes vasoconstriction, thus leading to vasodilation. We showed that in human and rat arterial myocytes, membrane depolarization rapidly increased the cell surface abundance of auxiliary BK β1 subunits but not that of the pore-forming BKα channels...
May 9, 2017: Science Signaling
https://www.readbyqxmd.com/read/28487418/-science-signaling-podcast-for-9-may-2017-trafficking-of-bk-channel-subunits-in-arterial-myocytes
#10
Jonathan H Jaggar, Annalisa M VanHook
This Podcast features a conversation with Jonathan Jaggar, senior author of a Research Article that appears in the 9 May 2017 issue of Science Signaling , about trafficking of big potassium (BK) channel subunits in arterial myocytes. Depolarization of the arterial myocyte membrane causes a rise in intracellular calcium that stimulates the cell to contract, which leads to vasoconstriction. Membrane depolarization also activates BK channels, which allow potassium to flow out of the cell, thus repolarizing the membrane and promoting vasodilation...
May 9, 2017: Science Signaling
https://www.readbyqxmd.com/read/28428266/kca1-1-channels-regulate-%C3%AE-1-integrin-function-and-cell-adhesion-in-rheumatoid-arthritis-fibroblast-like-synoviocytes
#11
Mark R Tanner, Michael W Pennington, Teresina Laragione, Pércio S Gulko, Christine Beeton
Large-conductance calcium-activated potassium channel (KCa1.1; BK, Slo1, MaxiK, KCNMA1 ) is the predominant potassium channel expressed at the plasma membrane of rheumatoid arthritis fibroblast-like synoviocytes (RA-FLSs) isolated from the synovium of patients with RA. It is a critical regulator of RA-FLS migration and invasion and therefore represents an attractive target for the therapy of RA. However, the molecular mechanisms by which KCa1.1 regulates RA-FLS invasiveness have remained largely unknown. Here, we demonstrate that KCa1...
August 2017: FASEB Journal: Official Publication of the Federation of American Societies for Experimental Biology
https://www.readbyqxmd.com/read/28416688/knockout-of-the-lrrc26-subunit-reveals-a-primary-role-of-lrrc26-containing-bk-channels-in-secretory-epithelial-cells
#12
Chengtao Yang, Vivian Gonzalez-Perez, Taro Mukaibo, James E Melvin, Xiao-Ming Xia, Christopher J Lingle
Leucine-rich-repeat-containing protein 26 (LRRC26) is the regulatory γ1 subunit of Ca(2+)- and voltage-dependent BK-type K(+) channels. BK channels that contain LRRC26 subunits are active near normal resting potentials even without Ca(2+), suggesting they play unique physiological roles, likely limited to very specific cell types and cellular functions. By using Lrrc26 KO mice with a β-gal reporter, Lrrc26 promoter activity is found in secretory epithelial cells, especially acinar epithelial cells in lacrimal and salivary glands, and also goblet and Paneth cells in intestine and colon, although absent from neurons...
May 2, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28373283/distinct-domains-of-the-%C3%AE-1-subunit-cytosolic-n-terminus-control-surface-expression-and-functional-properties-of-large-conductance-calcium-activated-potassium-bk-channels
#13
Lie Chen, Danlei Bi, Zen Huat Lu, Heather McClafferty, Michael J Shipston
The properties and function of large-conductance calcium- and voltage-activated potassium (BK) channels are modified by the tissue-specific expression of regulatory β1-subunits. Although the short cytosolic N-terminal domain of the β1-subunit is important for controlling both BK channel trafficking and function, whether the same, or different, regions of the N terminus control these distinct processes remains unknown. Here we demonstrate that the first six N-terminal residues including Lys-3, Lys-4, and Leu-5 are critical for controlling functional regulation, but not trafficking, of BK channels...
May 26, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28202492/gating-ring-strengthens-marriage-of-bk-channel-voltage-sensing-to-pore-opening
#14
Caitlin Sedwick
A new JGP study shows that the gating ring helps the voltage-sensing domain open the BK channel's pore.
March 6, 2017: Journal of General Physiology
https://www.readbyqxmd.com/read/28196879/deletion-of-cytosolic-gating-ring-decreases-gate-and-voltage-sensor-coupling-in-bk-channels
#15
Guohui Zhang, Yanyan Geng, Yakang Jin, Jingyi Shi, Kelli McFarland, Karl L Magleby, Lawrence Salkoff, Jianmin Cui
Large conductance Ca2+ -activated K+ channels (BK channels) gate open in response to both membrane voltage and intracellular Ca2+ The channel is formed by a central pore-gate domain (PGD), which spans the membrane, plus transmembrane voltage sensors and a cytoplasmic gating ring that acts as a Ca2+ sensor. How these voltage and Ca2+ sensors influence the common activation gate, and interact with each other, is unclear. A previous study showed that a BK channel core lacking the entire cytoplasmic gating ring (Core-MT) was devoid of Ca2+ activation but retained voltage sensitivity (Budelli et al...
March 6, 2017: Journal of General Physiology
https://www.readbyqxmd.com/read/28195225/a-novel-bk-channel-targeted-peptide-suppresses-sound-evoked-activity-in-the-mouse-inferior-colliculus
#16
L L Scott, E J Brecht, A Philpo, S Iyer, N S Wu, S J Mihic, R W Aldrich, J Pierce, J P Walton
Large conductance calcium-activated (BK) channels are broadly expressed in neurons and muscle where they modulate cellular activity. Decades of research support an interest in pharmaceutical applications for modulating BK channel function. Here we report a novel BK channel-targeted peptide with functional activity in vitro and in vivo. This 9-amino acid peptide, LS3, has a unique action, suppressing channel gating rather than blocking the pore of heterologously expressed human BK channels. With an IC50 in the high picomolar range, the apparent affinity is higher than known high affinity BK channel toxins...
February 14, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28165042/relationship-between-auxiliary-gamma-subunits-and-mallotoxin-on-bk-channel-modulation
#17
Xin Guan, Qin Li, Jiusheng Yan
The large-conductance, calcium- and voltage-activated K+ (BK) channel consists of the pore-forming α subunits (BKα) and auxiliary subunits. The auxiliary γ1-3 subunits potently modulate the BK channel by shifting its voltage-dependence of channel activation toward the hyperpolarizing direction by approximately 145 mV (γ1), 100 mV (γ2), and 50 mV (γ3). Mallotoxin is a potent small-molecule BK channel activator. We analyzed the relationship between mallotoxin and the γ subunits in their BK channel-activating effects in membrane patches excised from HEK-293 cells...
February 6, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28090300/bk-channels-in-rat-and-human-pulmonary-smooth-muscle-cells-are-bk%C3%AE-%C3%AE-1-functional-complexes-lacking-the-oxygen-sensitive-stress-axis-regulated-exon-insert
#18
Neil D Detweiler, Li Song, Samantha J McClenahan, Rachel J Versluis, Sujay V Kharade, Richard C Kurten, Sung W Rhee, Nancy J Rusch
A loss of K(+) efflux in pulmonary arterial smooth muscle cells (PASMCs) contributes to abnormal vasoconstriction and PASMC proliferation during pulmonary hypertension (PH). Activation of high-conductance Ca(2+)-activated (BK) channels represents a therapeutic strategy to restore K(+) efflux to the affected PASMCs. However, the properties of BK channels in PASMCs-including sensitivity to BK channel openers (BKCOs)-are poorly defined. The goal of this study was to compare the properties of BK channels between PASMCs of normoxic (N) and chronic hypoxic (CH) rats and then explore key findings in human PASMCs...
December 2016: Pulmonary Circulation
https://www.readbyqxmd.com/read/27807200/molecular-determinants-of-bk-channel-functional-diversity-and-functioning
#19
REVIEW
Ramon Latorre, Karen Castillo, Willy Carrasquel-Ursulaez, Romina V Sepulveda, Fernando Gonzalez-Nilo, Carlos Gonzalez, Osvaldo Alvarez
Large-conductance Ca2+- and voltage-activated K+ (BK) channels play many physiological roles ranging from the maintenance of smooth muscle tone to hearing and neurosecretion. BK channels are tetramers in which the pore-forming α subunit is coded by a single gene (Slowpoke, KCNMA1). In this review, we first highlight the physiological importance of this ubiquitous channel, emphasizing the role that BK channels play in different channelopathies. We next discuss the modular nature of BK channel-forming protein, in which the different modules (the voltage sensor and the Ca2+ binding sites) communicate with the pore gates allosterically...
January 2017: Physiological Reviews
https://www.readbyqxmd.com/read/27806944/the-mechanosensitive-bk%C3%AE-%C3%AE-1-channel-localizes-to-cilia-of-principal-cells-in-rabbit-cortical-collecting-duct-ccd
#20
Rolando Carrisoza-Gaytán, Lijun Wang, Carlos Schreck, Thomas R Kleyman, Wen-Hui Wang, Lisa M Satlin
Within the CCD of the distal nephron of the rabbit, the BK (maxi K) channel mediates Ca2+ - and/or stretch-dependent flow-induced K+ secretion (FIKS) and contributes to K+ adaptation in response to dietary K+ loading. An unresolved question is whether BK channels in intercalated cells (ICs) and/or principal cells (PCs) in the CCD mediate these K+ secretory processes. In support of a role for ICs in FIKS is the higher density of immunoreactive apical BKα (pore-forming subunit) and functional BK channel activity than detected in PCs, and an increase in IC BKα expression in response to a high-K+ diet...
January 1, 2017: American Journal of Physiology. Renal Physiology
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