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voltage gated potassium channel

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https://www.readbyqxmd.com/read/28327344/direct-activation-of-ca-2-and-voltage-gated-potassium-channels-of-large-conductance-by-anandamide-in-endothelial-cells-does-not-support-the-presence-of-endothelial-atypical-cannabinoid-receptor
#1
Alexander I Bondarenko, Olga Panasiuk, Iryna Okhai, Fabrizio Montecucco, Karim J Brandt, Francois Mach
Endocannabinoid anandamide induces endothelium-dependent relaxation commonly attributed to stimulation of the G-protein coupled endothelial anandamide receptor. The study addressed the receptor-independent effect of anandamide on large conductance Ca(2+)-dependent K(+) channels expressed in endothelial cell line EA.hy926. Under resting conditions, 10µM anandamide did not significantly influence the resting membrane potential. In a Ca(2+)-free solution the cells were depolarized by ~10 mV. Further administration of 10µM anandamide hyperpolarized the cells by ~8 mV...
March 19, 2017: European Journal of Pharmacology
https://www.readbyqxmd.com/read/28325748/halogenated-ether-alcohol-and-alkane-anesthetics-activate-task-3-tandem-pore-potassium-channels-likely-through-a-common-mechanism
#2
Anita Luethy, James D Boghosian, Rithu Srikantha, Joseph Cotten
TASK-3 (KCNK9) tandem pore potassium channel function is activated by halogenated anesthetics through binding at a putative anesthetic binding cavity. To understand pharmacological requirements for TASK-3 activation, we studied the concentration-response of TASK-3 to several anesthetics (isoflurane, desflurane, sevoflurane, halothane, α-chloralose, 2,2,2-trichloroethanol(TCE), and chloral hydrate), to ethanol, and to a panel of halogenated methanes and alcohols. We used mutagenesis to probe the anesthetic binding cavity as observed in a TASK-3 homology model...
March 21, 2017: Molecular Pharmacology
https://www.readbyqxmd.com/read/28322444/identification-and-characterization-of-site-specific-n-glycosylation-in-the-potassium-channel-kv3-1b
#3
Paul Christian Vicente, Jin Young Kim, Jeong-Ju Ha, Min-Young Song, Hyun-Kyung Lee, Dong-Hyun Kim, Jin-Sung Choi, Kang-Sik Park
The potassium ion channel Kv3.1b is a member of a family of voltage-gated ion channels that are glycosylated in their mature form. In the present study, we demonstrate the impact of N-glycosylation at specific asparagine residues on the trafficking of the Kv3.1b protein. Large quantities of asparagine 229 (N229)-glycosylated Kv3.1b reached the plasma membrane, whereas N220-glycosylated and unglycosylated Kv3.1b were mainly retained in the endoplasmic reticulum (ER). These ER-retained Kv3.1b proteins were susceptible to degradation when co-expressed with calnexin, whereas Kv3...
March 21, 2017: Journal of Cellular Physiology
https://www.readbyqxmd.com/read/28316759/fourier-analysis-of-conservation-patterns-in-protein-secondary-structure
#4
Ashok Palaniappan, Eric Jakobsson
Residue conservation is a common observation in alignments of protein families, underscoring positions important in protein structure and function. Though many methods measure the level of conservation of particular residue positions, currently we do not have a way to study spatial oscillations occurring in protein conservation patterns. It is known that hydrophobicity shows spatial oscillations in proteins, which is characterized by computing the hydrophobic moment of the protein domains. Here, we advance the study of moments of conservation of protein families to know whether there might exist spatial asymmetry in the conservation patterns of regular secondary structures...
2017: Computational and Structural Biotechnology Journal
https://www.readbyqxmd.com/read/28315020/novel-biomarkers-for-non-functioning-invasive-pituitary-adenomas-were-identified-by-using-analysis-of-micrornas-expression-profile
#5
Silin Wu, Ye Gu, Yuying Huang, Tyh-Chai Wong, Hailin Ding, Tengfei Liu, Yu Zhang, Xiaobiao Zhang
The microRNAs (miRNAs) are involved in multiple pathological processes among various types of tumors. However, the functions of miRNAs in benign brain tumors are largely unexplored. In order to explore the pathogenesis of the invasiveness in non-functional pituitary adenoma (NFPA), the miRNAs expression profile was analyzed between invasive and non-invasive non-functional pituitary adenoma by miRNAs microarray. Six most significant differentially expressed miRNAs were identified including four upregulated miRNAs hsa-miR-181b-5p, hsa-miR-181d, hsa-miR-191-3p, and hsa-miR-598 and two downregulated miRNAs hsa-miR-3676-5p and hsa-miR-383...
March 17, 2017: Biochemical Genetics
https://www.readbyqxmd.com/read/28314880/comparative-study-of-the-structure-and-interaction-of-the-pore-helices-of-the-herg-and-kv1-5-potassium-channels-in-model-membranes
#6
Maïwenn Beaugrand, Alexandre A Arnold, Steve Bourgault, Philip T F Williamson, Isabelle Marcotte
The hERG channel is a voltage-gated potassium channel found in cardiomyocytes that contributes to the repolarization of the cell membrane following the cardiac action potential, an important step in the regulation of the cardiac cycle. The lipids surrounding K(+) channels have been shown to play a key role in their regulation, with anionic lipids shown to alter gating properties. In this study, we investigate how anionic lipids interact with the pore helix of hERG and compare the results with those from Kv1...
March 17, 2017: European Biophysics Journal: EBJ
https://www.readbyqxmd.com/read/28300158/the-receptor-like-pseudokinase-mrh1-interacts-with-the-voltage-gated-potassium-channel-akt2
#7
Kamil Sklodowski, Janin Riedelsberger, Natalia Raddatz, Gonzalo Riadi, Julio Caballero, Isabelle Chérel, Waltraud Schulze, Alexander Graf, Ingo Dreyer
The potassium channel AKT2 plays important roles in phloem loading and unloading. It can operate as inward-rectifying channel that allows H(+)-ATPase-energized K(+) uptake. Moreover, through reversible post-translational modifications it can also function as an open, K(+)-selective channel, which taps a 'potassium battery', providing additional energy for transmembrane transport processes. Knowledge about proteins involved in the regulation of the operational mode of AKT2 is very limited. Here, we employed a large-scale yeast two-hybrid screen in combination with fluorescence tagging and null-allele mutant phenotype analysis and identified the plasma membrane localized receptor-like kinase MRH1/MDIS2 (AT4G18640) as interaction partner of AKT2...
March 16, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28283543/kcnq-smit-complex-formation-facilitates-ion-channel-solute-transporter-cross-talk
#8
Daniel L Neverisky, Geoffrey W Abbott
Voltage-gated potassium channels formed by KCNQ2 and KCNQ3 are essential for normal neuronal excitability. KCNQ2/3 channel activity is augmented in vivo by phosphatidylinositol 4,5-bisphosphate (PIP2), which is generated from myo-inositol, an osmolyte transported into cells by sodium-dependent myo-inositol transporters (SMITs). Here, we discovered that KCNQ2/3 channels isoform-specifically colocalize with SMIT1 and SMIT2 at sciatic nerve nodes of Ranvier and in axon initial segments, and form channel-transporter complexes in vitro and in vivo KCNQ2/3 coexpression protected SMIT1 activity from the otherwise inhibitory effects of cellular depolarization imposed by elevating extracellular [K(+)], and KCNQ2 was required for potentiation of SMIT activity by myo-inositol preincubation...
March 10, 2017: FASEB Journal: Official Publication of the Federation of American Societies for Experimental Biology
https://www.readbyqxmd.com/read/28280418/intracellular-calcium-dependent-regulation-of-the-sperm-specific-calcium-activated-potassium-channel-hslo3-by-the-bkca-activator-ldd175
#9
Tharaka Darshana Wijerathne, Jihyun Kim, Dongki Yang, Kyu Pil Lee
Plasma membrane hyperpolarization associated with activation of Ca(2+)-activated K(+) channels plays an important role in sperm capacitation during fertilization. Although Slo3 (slowpoke homologue 3), together with the auxiliary γ2-subunit, LRRC52 (leucine-rich-repeat-containing 52), is known to mediate the pH-sensitive, sperm-specific K(+) current KSper in mice, the molecular identity of this channel in human sperm remains controversial. In this study, we tested the classical BKCa activators, NS1619 and LDD175, on human Slo3, heterologously expressed in HEK293 cells together with its functional interacting γ2 subunit, hLRRC52...
March 2017: Korean Journal of Physiology & Pharmacology
https://www.readbyqxmd.com/read/28273916/herg-s4-s5-linker-acts-as-a-voltage-dependent-ligand-that-binds-to-the-activation-gate-and-locks-it-in-a-closed-state
#10
Olfat A Malak, Zeineb Es-Salah-Lamoureux, Gildas Loussouarn
Delayed-rectifier potassium channels (hERG and KCNQ1) play a major role in cardiac repolarization. These channels are formed by a tetrameric pore (S5-S6) surrounded by four voltage sensor domains (S1-S4). Coupling between voltage sensor domains and the pore activation gate is critical for channel voltage-dependence. However, molecular mechanisms remain elusive. Herein, we demonstrate that covalently binding, through a disulfide bridge, a peptide mimicking the S4-S5 linker (S4-S5L) to the channel S6 C-terminus (S6T) completely inhibits hERG...
December 2017: Scientific Reports
https://www.readbyqxmd.com/read/28272206/limbic-encephalitis-associated-with-anti-nh2-terminal-of-%C3%AE-enolase-antibodies-a-clinical-subtype-of-hashimoto-encephalopathy
#11
Toru Kishitani, Akiko Matsunaga, Masamichi Ikawa, Kouji Hayashi, Osamu Yamamura, Tadanori Hamano, Osamu Watanabe, Keiko Tanaka, Yasunari Nakamoto, Makoto Yoneda
Several types of autoantibodies have been reported in autoimmune limbic encephalitis (LE), such as antibodies against the voltage-gated potassium channel (VGKC) complex including leucine-rich glioma inactivated 1 (LGI1). We recently reported a patient with autoimmune LE and serum anti-NH2-terminal of α-enolase (NAE) antibodies, a specific diagnostic marker for Hashimoto encephalopathy (HE), who was diagnosed with HE based on the presence of antithyroid antibodies and responsiveness to immunotherapy. This case suggests that LE patients with antibodies to both the thyroid and NAE could be diagnosed with HE and respond to immunotherapy...
March 2017: Medicine (Baltimore)
https://www.readbyqxmd.com/read/28265056/hysteresis-of-kcsa-potassium-channel-s-activation-deactivation-gating-is-caused-by-structural-changes-at-the-channel-s-selectivity-filter
#12
Cholpon Tilegenova, D Marien Cortes, Luis G Cuello
Mode-shift or hysteresis has been reported in ion channels. Voltage-shift for gating currents is well documented for voltage-gated cation channels (VGCC), and it is considered a voltage-sensing domain's (VSD) intrinsic property. However, uncoupling the Shaker K(+) channel's pore domain (PD) from the VSD prevented the mode-shift of the gating currents. Consequently, it was proposed that an open-state stabilization of the PD imposes a mechanical load on the VSD, which causes its mode-shift. Furthermore, the mode-shift displayed by hyperpolarization-gated cation channels is likely caused by structural changes at the channel's PD similar to those underlying C-type inactivation...
March 6, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28264681/ion-channels-or-aquaporins-as-novel-molecular-targets-in-gastric-cancer
#13
REVIEW
Jianling Xia, Hongqiang Wang, Shi Li, Qinghui Wu, Li Sun, Hongxiang Huang, Ming Zeng
Gastric cancer (GC) is a common disease with few effective treatment choices and poor prognosis, and has the second-highest mortality rates among all cancers worldwide. Dysregulation and/or malfunction of ion channels or aquaporins (AQPs) are common in various human cancers. Furthermore, ion channels are involved in numerous important aspects of the tumor aggressive phonotype, such as proliferation, cell cycle, apoptosis, motility, migration, and invasion. Indeed, by localizing in the plasma membrane, ion channels or AQPs can sense and respond to extracellular environment changes; thus, they play a crucial role in cell signaling and cancer progression...
March 6, 2017: Molecular Cancer
https://www.readbyqxmd.com/read/28264196/molecular-basis-of-ancestral-vertebrate-electroreception
#14
Nicholas W Bellono, Duncan B Leitch, David Julius
Elasmobranch fishes, including sharks, rays, and skates, use specialized electrosensory organs called ampullae of Lorenzini to detect extremely small changes in environmental electric fields. Electrosensory cells within these ampullae can discriminate and respond to minute changes in environmental voltage gradients through an unknown mechanism. Here we show that the voltage-gated calcium channel CaV1.3 and the big conductance calcium-activated potassium (BK) channel are preferentially expressed by electrosensory cells in little skate (Leucoraja erinacea) and functionally couple to mediate electrosensory cell membrane voltage oscillations, which are important for the detection of specific, weak electrical signals...
March 16, 2017: Nature
https://www.readbyqxmd.com/read/28252570/potassium-channel-candidate-genes-predict-the-development-of-secondary-lymphedema-following-breast-cancer-surgery
#15
Betty Smoot, Kord M Kober, Steven M Paul, Jon D Levine, Gary Abrams, Judy Mastick, Kimberly Topp, Yvette P Conley, Christine A Miaskowski
BACKGROUND: Potassium (K) channels play an important role in lymph pump activity, lymph formation, lymph transport, and the functions of lymph nodes. No studies have examined the relationship between K channel candidate genes and the development of secondary lymphedema (LE). OBJECTIVE: The study purpose was to evaluate for differences in genotypic characteristics in women who did (n = 155) or did not (n = 387) develop upper extremity LE following breast cancer treatment based on an analysis of single-nucleotide polymorphisms (SNPs) and haplotypes in 10 K channel genes...
March 2017: Nursing Research
https://www.readbyqxmd.com/read/28250418/pado-a-fluorescent-protein-with-proton-channel-activity-can-optically-monitor-membrane-potential-intracellular-ph-and-map-gap-junctions
#16
Bok Eum Kang, Bradley J Baker
An in silico search strategy was developed to identify potential voltage-sensing domains (VSD) for the development of genetically encoded voltage indicators (GEVIs). Using a conserved charge distribution in the S2 α-helix, a single in silico search yielded most voltage-sensing proteins including voltage-gated potassium channels, voltage-gated calcium channels, voltage-gated sodium channels, voltage-gated proton channels, and voltage-sensing phosphatases from organisms ranging from mammals to bacteria and plants...
July 2016: Scientific Reports
https://www.readbyqxmd.com/read/28248701/autoimmune-encephalitis-with-anti-leucine-rich-glioma-inactivated-1-or-anti-contactin-associated-protein-like-2-antibodies-formerly-called-voltage-gated-potassium-channel-complex-antibodies
#17
Anna E M Bastiaansen, Agnes van Sonderen, Maarten J Titulaer
PURPOSE OF REVIEW: Twenty years since the discovery of voltage-gated potassium channel (VGKC)-related autoimmunity; it is currently known that the antibodies are not directed at the VGKC itself but to two closely associated proteins, anti-leucine-rich glioma-inactivated 1 (LGI1) and contactin-associated protein-like 2 (Caspr2). Antibodies to LGI1 and Caspr2 give well-described clinical phenotypes. Anti-LGI1 encephalitis patients mostly have limbic symptoms, and anti-Caspr2 patients have variable syndromes with both central and peripheral symptoms...
February 28, 2017: Current Opinion in Neurology
https://www.readbyqxmd.com/read/28248292/potassium-channels-kv1-3-and-kca3-1-cooperatively-and-compensatorily-regulate-antigen-specific-memory-t-cell-functions
#18
Eugene Y Chiang, Tianbo Li, Surinder Jeet, Ivan Peng, Juan Zhang, Wyne P Lee, Jason DeVoss, Patrick Caplazi, Jun Chen, Søren Warming, David H Hackos, Susmith Mukund, Christopher M Koth, Jane L Grogan
Voltage-gated Kv1.3 and Ca(2+)-dependent KCa3.1 are the most prevalent K(+) channels expressed by human and rat T cells. Despite the preferential upregulation of Kv1.3 over KCa3.1 on autoantigen-experienced effector memory T cells, whether Kv1.3 is required for their induction and function is unclear. Here we show, using Kv1.3-deficient rats, that Kv1.3 is involved in the development of chronically activated antigen-specific T cells. Several immune responses are normal in Kv1.3 knockout (KO) rats, suggesting that KCa3...
March 1, 2017: Nature Communications
https://www.readbyqxmd.com/read/28242439/kv3-1-kv3-2-channel-positive-modulators-enable-faster-activating-kinetics-and-increase-firing-frequency-in-fast-spiking-gabaergic-interneurons
#19
Kim Boddum, Charlotte Hougaard, Julie Xiao-Ying Lin, Nadia Lybøl von Schoubye, Henrik Sindal Jensen, Morten Grunnet, Thomas Jespersen
Due to their fast kinetic properties, Kv3.1 voltage gated potassium channels are important in setting and controlling firing frequency in neurons and pivotal in generating high frequency firing of interneurons. Pharmacological activation of Kv3.1 channels may possess therapeutic potential for treatment of epilepsy, hearing disorders, schizophrenia and cognitive impairments. Here we thoroughly investigate the selectivity and positive modulation of the two small molecules, EX15 and RE01, on Kv3 channels. Selectivity studies, conducted in Xenopus laevis oocytes confirmed a positive modulatory effect of the two compounds on Kv3...
February 24, 2017: Neuropharmacology
https://www.readbyqxmd.com/read/28235848/patients-with-long-qt-syndrome-due-to-impaired-herg-encoded-kv11-1-potassium-channel-have-exaggerated-endocrine-pancreatic-and-incretin-function-associated-with-reactive-hypoglycemia
#20
Louise Hyltén-Cavallius, Eva W Iepsen, Nicolai J Wewer Albrechtsen, Mathilde Svendstrup, Anniek F Lubberding, Bolette Hartmann, Thomas Jespersen, Allan Linneberg, Michael Christiansen, Henrik Vestergaard, Oluf Pedersen, Jens J Holst, Jørgen K Kanters, Torben Hansen, Signe S Torekov
Background -Loss-of-function mutations in hERG (encoding the Kv11.1 voltage-gated potassium channel) cause long QT syndrome (LQT2) due to prolonged cardiac repolarization. However, Kv11.1 is also present in pancreatic α and β cells and intestinal L and K cells, secreting glucagon, insulin, and the incretins glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), respectively. These hormones are crucial for glucose regulation and LQTS may cause disturbed glucose regulation. We measured secretion of these hormones and cardiac repolarization in response to glucose ingestion in LQT2 patients with functional mutations in hERG and matched healthy participants, testing the hypothesis that LQT2 patients have increased incretin and β cell- and decreased α cell function and thus lower glucose levels...
February 24, 2017: Circulation
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