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Ca2+ single

Le Xu, Venkat R Chirasani, Jordan S Carter, Daniel A Pasek, Nikolay V Dokholyan, Naohiro Yamaguchi, Gerhard Meissner
Cryo-electron micrograph studies recently have identified a Ca2+-binding site in the 2,200-kDa ryanodine receptor ion channel (RyR1) in skeletal muscle.[MS2]  To clarify the role of this site in regulating RyR1 activity, here we applied mutational, electrophysiological, and computational methods. Three amino acid residues that interact directly with Ca2+ were replaced, and these RyR1 variants were expressed in HEK293 cells. Single-site RyR1-E3893Q, E3893V, E3967Q, E3967V, and T5001A variants and double-site RyR1-E3893Q/E3967Q and E3893V/E3967V variants displayed cellular Ca2+ release in response to caffeine, which indicated that they retained functionality as caffeine-sensitive, Ca2+-conducting channels in the HEK293 cell system...
October 19, 2018: Journal of Biological Chemistry
Cuifeng Ying, Jared Houghtaling, Olivia M Eggenberger, Anirvan Guha, Dr Peter Nirmalraj, Saurabh Awasthi, Jianguo Tian, Michael Mayer
Nanopores with diameters from 20-50 nm in silicon nitride (SiNx) windows are useful for single-molecule studies of globular macromolecules. While controlled breakdown (CBD) is gaining popularity as a method for fabricating nanopores with reproducible size control and broad accessibility, attempts to fabricate large nanopores with diameters exceeding ~20 nm via breakdown often result in undesirable formation of multiple nanopores in SiNx membranes. To reduce the probability of producing multiple pores, we combined two strategies: laser-assisted breakdown and controlled pore enlargement by limiting the applied voltage...
October 18, 2018: ACS Nano
Jorge Ricardo Apolinario Macedo Cunha, Taina Tervahauta, Renata van der Weijden, Hardy Temmink, Lucia Hernandez Leal, Grietje Zeeman, Cees J N Buisman
Simultaneous recovery of calcium phosphate granules (CaP granules) and methane in anaerobic treatment of source separated black water (BW) has been previously demonstrated. The exact mechanism behind the accumulation of calcium phosphate (Cax (PO4 )y ) in CaP granules during black water treatment was investigated in this study by examination of the interface between the outer anaerobic biofilm and the core of CaP granules. A key factor in this process is the pH profile in CaP granules, which increases from the edge (7...
October 17, 2018: Environmental Science & Technology
Sebastian Beck, Jing Yu-Strzelczyk, Dennis Pauls, Oana M Constantin, Christine E Gee, Nadine Ehmann, Robert J Kittel, Georg Nagel, Shiqiang Gao
Optogenetic manipulation of cells or living organisms became widely used in neuroscience following the introduction of the light-gated ion channel channelrhodopsin-2 (ChR2). ChR2 is a non-selective cation channel, ideally suited to depolarize and evoke action potentials in neurons. However, its calcium (Ca2+ ) permeability and single channel conductance are low and for some applications longer-lasting increases in intracellular Ca2+ might be desirable. Moreover, there is need for an efficient light-gated potassium (K+ ) channel that can rapidly inhibit spiking in targeted neurons...
2018: Frontiers in Neuroscience
Wenjuan Zou, Jiajun Fu, Haining Zhang, Kang Du, Wenming Huang, Junwei Yu, Shitian Li, Yuedan Fan, Howard A Baylis, Shangbang Gao, Rui Xiao, Wei Ji, Lijun Kang, Tao Xu
How neurons are capable of decoding stimulus intensity and translate this information into complex behavioral outputs is poorly defined. Here, we demonstrate that the C. elegans interneuron AIB regulates two types of behaviors: reversal initiation and feeding suppression in response to different concentrations of quinine. Low concentrations of quinine are decoded in AIB by a low-threshold, fast-inactivation glutamate receptor GLR-1 and translated into reversal initiation. In contrast, high concentrations of quinine are decoded by a high-threshold, slow-inactivation glutamate receptor GLR-5 in AIB...
October 17, 2018: Nature Communications
Emily Lorenzen, Emilie Ceraudo, Yamina A Berchiche, Carlos A Rico, Alexandre Fürstenberg, Thomas P Sakmar, Thomas Huber
Chemokines and some chemical analogs of chemokines prevent cellular HIV-1 entry when bound to the HIV-1 coreceptors C-C chemokine receptor 5 (CCR5) or C-X-C chemokine receptor 4 (CXCR4), which are G protein-coupled receptors (GPCRs). The ideal HIV-1 entry blocker targeting the coreceptors would display ligand bias and avoid activating G protein-mediated pathways that lead to inflammation. We compared CCR5-dependent activation of second messenger pathways in a single cell line. We studied two endogenous chemokines [RANTES (also known as CCL5) and MIP-1α (also known as CCL3)] and four chemokine analogs of RANTES (5P12-, 5P14-, 6P4-, and PSC-RANTES)...
October 16, 2018: Science Signaling
Nicholas Mikolajewicz, Elizabeth A Zimmermann, Bettina M Willie, Svetlana V Komarova
Bone cells sense and actively adapt to physical perturbations to prevent critical damage. ATP release is among the earliest cellular responses to mechanical stimulation. Mechanical stimulation of a single murine osteoblast led to the release of 70 {plus minus} 24 amole ATP, which stimulated calcium responses in neighboring cells. Osteoblasts contained ATP-rich vesicles that were released upon mechanical stimulation. Surprisingly, interventions that promoted vesicular release reduced ATP release, while inhibitors of vesicular release potentiated ATP release...
October 16, 2018: ELife
Annette C Dolphin
This review will first describe the importance of Ca2+ entry for function of excitable cells, and the subsequent discovery of voltage-activated calcium conductances in these cells. This finding was rapidly followed by the identification of multiple subtypes of calcium conductance in different tissues. These were initially termed low- and high-voltage activated currents, but were then further subdivided into L-, N-, PQ-, R and T-type calcium currents on the basis of differing pharmacology, voltage-dependent and kinetic properties, and single channel conductance...
October 2, 2018: Brain and Neuroscience Advances
Gregory E Miner, Rutilio Fratti
During in vitro homotypic yeast vacuole fusion Ca2+ is transported into and out of the organelle lumen. In vitro, Ca2+ is taken up from the medium by vacuoles upon the addition of ATP. During the docking stage of vacuole fusion Ca2+ is effluxed from the lumen upon the formation of trans-SNARE complexes between vesicles. Here we describe a real-time fluorescence-based assay to monitor the transport of this cation using purified organelles. Extraluminal Ca2+ is detected when the cation binds the low-affinity fluorescent dye Fluo-4 dextran...
2019: Methods in Molecular Biology
Corina DeKraker, Eric Boucher, Craig A Mandato
Cytokinesis and single-cell wound repair both involve contractile assemblies of filamentous actin (F-actin) and myosin II organized into characteristic ring-like arrays. The assembly of these actomyosin contractile rings (CRs) is specified spatially and temporally by small Rho GTPases, which trigger local actin polymerization and myosin II contractility via a variety of downstream effectors. We now have a much clearer view of the Rho GTPase signalling cascade that leads to the formation of CRs, but some factors involved in CR positioning, assembly, and function remain poorly understood...
October 12, 2018: Anatomical Record: Advances in Integrative Anatomy and Evolutionary Biology
Somayeh Mojarad Kalkhoran, Sarah Heather Jane Chow, Jagdeep Singh Walia, Cynthia Gershome, Nickolas Saraev, BaRun Kim, Damon Poburko
ATP and norepinephrine (NE) are co-released from peripheral sympathetic nerve terminals. Whether they are stored in the same vesicles has been debated for decades. Preferential dependence of NE or ATP release on Ca2+ influx through specific CaV2 isoforms suggests that NE and ATP are stored in separate vesicle pools, but simultaneous imaging of NE and ATP containing vesicles within single varicosities has not been reported. We conducted immunohistochemical studies of Vesicular Monoamine Transporter 2 (VMAT2/SLC18A2) and Vesicular Nucleotide Translocase (VNUT/SLC17A9) as markers of vesicles containing NE and ATP in sympathetic nerves of the rat tail artery...
October 12, 2018: American Journal of Physiology. Heart and Circulatory Physiology
Andrew S DiChiara, Rasia C Li, Patreece H Suen, Azade S Hosseini, Rebecca J Taylor, Alexander F Weickhardt, Diya Malhotra, Darrell R McCaslin, Matthew D Shoulders
Fundamental questions regarding collagen biosynthesis, especially with respect to the molecular origins of homotrimeric versus heterotrimeric assembly, remain unanswered. Here, we demonstrate that the presence or absence of a single cysteine in type-I collagen's C-propeptide domain is a key factor governing the ability of a given collagen polypeptide to stably homotrimerize. We also identify a critical role for Ca2+ in non-covalent collagen C-propeptide trimerization, thereby priming the protein for disulfide-mediated covalent immortalization...
October 11, 2018: Nature Communications
Tianxiao Zhang, Li Zhu, Tong Ni, Dan Liu, Gang Chen, Zhilan Yan, Huali Lin, Fanglin Guan, John P Rice
Schizophrenia (SCZ) is a devastating mental disorder affecting approximately 1% of the worldwide population. Early studies have indicated that genetics plays an important role in the onset and development of SCZ. Accumulating evidence supports that SCZ is linked to abnormalities of synapse transmission and synaptic plasticity. Voltage-gated calcium channel (VGCC) subunits are critical for mediating intracellular Ca2 +  influx and therefore are responsible for changing neuronal excitability and synaptic plasticity...
October 3, 2018: Journal of Psychiatric Research
Xuerui Tian, Lin Hou, Jiaojiao Wang, Xing Xin, Heng Zhang, Yuanyuan Ma, Yali Wang, Lina Zhang, Zhangang Han
New Na-bridged phosphomolybdates (H2en)12[{Na0.8K0.2(H2O)}2{Na[Mo6O12(OH)3(HPO4)2(PO4)2]2}2]·7H2O (1), (H2bpp)2[{Sr2(H2O)4}{Na3(H2O)10}{Na[Mo6O12(OH)3(HPO4)3(PO4)]2}]·2H2O (2), and (H2bpp)6 [{Ca2(H2O)4}{Na2(H2O)4}{Na[Mo6O12(OH)3(HPO4)3(PO4)]2}2] (3) (en = ethylenediamine, bpp = 1,3-bi(4-pyridyl)propane), were synthesized by a hydrothermal method and characterized. Single-crystal X-ray diffraction analysis revealed that the three hybrids were composed of fully reduced 'hourglass-shaped' {Na[PV4MoV6X31]2}n- (X = O/OH) clusters and N-containing organic cations...
October 11, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Kazuo Kurokawa, Akihiko Nakano
The endoplasmic reticulum (ER) is a multifunctional organelle, including secretory protein biogenesis, lipid synthesis, drug metabolism, Ca2+ signaling, and so on. Since the ER is a single continuous membrane structure, it includes distinct zones responsible for its different functions. The export of newly synthesized proteins from the ER is facilitated via coat protein complex II (COPII)-coated vesicles, which form in specialized zones within the ER, called the ER exit sites (ERES) or transitional ER. In this review, we highlight recent advances in our understanding of the structural organization of ERES, the correlation between the ERES and Golgi organization, and the faithful cargo transport mechanism from the ERES to the Golgi...
October 10, 2018: Journal of Biochemistry
L K Seidlmayer, F Riediger, N Pagonas, P Nordbeck, O Ritter, B Sasko
BACKGROUND: Catecholaminergic polymorphic ventricular tachycardia is an inherited disease presenting with arrhythmic events during physical exercise or emotional stress. If untreated, catecholaminergic polymorphic ventricular tachycardia is a highly lethal condition: About 80% of affected individuals experience recurrent syncope, and 30% experience cardiac arrest. Catecholaminergic polymorphic ventricular tachycardia is caused by mutations in genes encoding ryanodine receptor type 2 (RyR2) and cardiac calsequestrin (CASQ2)...
October 9, 2018: Journal of Medical Case Reports
Yanli Wang, Chao Yuan, Bo Cui, Yawei Liu
The influences of 4 mono- and di-valent cations (K+ , Na+ , Mg2+ and Ca2+ ) on the mechanical, sol-gel transition and freeze-thaw properties of κ-carrageenan gel were investigated. Texture profile analysis results demonstrated that the texture behavior of gelatinized κ-carrageenan was obviously influenced by the cation types and concentrations and the influence of K+ was the greatest. The gelling temperature (Tg ) of κ-carrageenan gel showed a positive correlation with cation concentrations and the influence of K+ was still the largest...
December 15, 2018: Carbohydrate Polymers
Christian R Marks, Brian C Shonesy, Xiaohan Wang, Jason R Stephenson, Colleen Niswender, Roger J Colbran
Ca2+ calmodulin dependent protein kinase II (CaMKII) and metabotropic glutamate receptor 5 (mGlu5) are critical signaling molecules in synaptic plasticity and learning memory. Here, we demonstrate that mGlu5 is present in CaMKIIα complexes isolated from mouse forebrain. Further in vitro characterization showed that the membrane-proximal region of the C-terminal domain (CTD) of mGlu5a directly interacts with purified Thr286-autophosphorylated (activated) CaMKIIα. However, the binding of CaMKIIα to this CTD fragment is reduced by the addition of excess Ca2+/calmodulin or by additional CaMKIIα autophosphorylation at non-Thr286 sites...
October 3, 2018: Molecular Pharmacology
Adrián López-Vergara, José M Porras-Vázquez, Einar Vøllestad, Jesús Canales-Vazquez, Enrique R Losilla, David Marrero-López
La5.4 MoO11.1 proton conductors with different metal doping (Ca2+ , Sr2+ , Ba2+ , Ti4+ , Zr4+ , and Nb5+ ) have been prepared and structurally and electrically characterized. Different polymorphs are stabilized depending on the doping and cooling rate used during the synthesis process. The most interesting results are obtained for Nb-doping, La5.4 Mo1- x Nb x O11.1- x/2 , where single compounds are obtained in the compositional range 0 ≤ x ≤ 0.2. These materials are fully characterized by structural techniques such as X-ray and neutron powder diffraction and transmission electron microscopy, which independently confirm the changes of polymorphism...
October 3, 2018: Inorganic Chemistry
Joon-Chul Kim, Min-Jeong Son, Sun-Hee Woo
Myocardium is subjected to a variety of forces with each contraction, such as stretch, afterload, and shear stress, and adapts to those mechanical stimuli. These mechanical stimuli increase in heart failure, valvular heart disease and hypertension that are clinically associated with arrhythmia and myocyte remodeling. To understand cellular and molecular basis of mechanical stress-mediated cardiac dysfunction and remodeling, several experimental approaches have been successfully used in single cardiac myocytes...
September 29, 2018: Archives of Biochemistry and Biophysics
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