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https://www.readbyqxmd.com/read/28340354/mechanism-of-substrate-translocation-in-an-alternating-access-transporter
#1
Naomi R Latorraca, Nathan M Fastman, A J Venkatakrishnan, Wolf B Frommer, Ron O Dror, Liang Feng
Transporters shuttle molecules across cell membranes by alternating among distinct conformational states. Fundamental questions remain about how transporters transition between states and how such structural rearrangements regulate substrate translocation. Here, we capture the translocation process by crystallography and unguided molecular dynamics simulations, providing an atomic-level description of alternating access transport. Simulations of a SWEET-family transporter initiated from an outward-open, glucose-bound structure reported here spontaneously adopt occluded and inward-open conformations...
March 23, 2017: Cell
https://www.readbyqxmd.com/read/28339593/selective-pharmacological-augmentation-of-hippocampal-activity-produces-a-sustained-antidepressant-like-response-without-abuse-related-or-psychotomimetic-effects
#2
Flavia R Carreno, Gregory T Collins, Alan Frazer, Daniel J Lodge
Background: Selective augmentation of hippocampal activity in ways similar to that caused by ketamine may have therapeutic advantages over ketamine, which has psychotomimetic and reinforcing effects likely due to effects outside the hippocampus (i.e., off-target effects). Methods: Here we evaluated the antidepressant-like response to a negative allosteric modulator of α5 subunit- containing gamma aminobutyric acid subtype A receptors, L-655,708, as these receptors are expressed to a much greater extent in the hippocampus than in other brain areas...
January 25, 2017: International Journal of Neuropsychopharmacology
https://www.readbyqxmd.com/read/28339191/allosteric-activation-of-cytochrome-p450-3a4-via-progesterone-bioconjugation
#3
Vanja Polic, Karine Auclair
Human cytochrome P450 3A4 (CYP3A4) is responsible for the metabolism of the majority of drugs. As such, it is implicated in many adverse drug-drug and food-drug interactions, and is of significant interest to the pharmaceutical industry. This enzyme is known to simultaneously bind multiple ligands and display atypical enzyme kinetics, suggestive of allostery and cooperativity. As well, evidence of a postulated peripheral allosteric binding site has provoked debate around its significance and location. We report the use of bioconjugation to study the significance of substrate binding at the proposed allosteric site and its effect on CYP3A4 activity...
March 24, 2017: Bioconjugate Chemistry
https://www.readbyqxmd.com/read/28337324/discovery-of-gbt440-an-orally-bioavailable-r-state-stabilizer-of-sickle-cell-hemoglobin
#4
Brian Metcalf, Chihyuan Chuang, Kobina Dufu, Mira P Patel, Abel Silva-Garcia, Carl Johnson, Qing Lu, James R Partridge, Larysa Patskovska, Yury Patskovsky, Steven C Almo, Matthew P Jacobson, Lan Hua, Qing Xu, Stephen L Gwaltney, Calvin Yee, Jason Harris, Bradley P Morgan, Joyce James, Donghong Xu, Athiwat Hutchaleelaha, Kumar Paulvannan, Donna Oksenberg, Zhe Li
We report the discovery of a new potent allosteric effector of sickle cell hemoglobin, GBT440 (36), that increases the affinity of hemoglobin for oxygen and consequently inhibits its polymerization when subjected to hypoxic conditions. Unlike earlier allosteric activators that bind covalently to hemoglobin in a 2:1 stoichiometry, 36 binds with a 1:1 stoichiometry. Compound 36 is orally bioavailable and partitions highly and favorably into the red blood cell with a RBC/plasma ratio of ∼150. This partitioning onto the target protein is anticipated to allow therapeutic concentrations to be achieved in the red blood cell at low plasma concentrations...
March 9, 2017: ACS Medicinal Chemistry Letters
https://www.readbyqxmd.com/read/28337254/amp-activated-protein-kinase-and-energy-balance-in-breast-cancer
#5
REVIEW
Hong Zhao, Yelda C Orhan, Xiaoming Zha, Ecem Esencan, Robert T Chatterton, Serdar E Bulun
Cancer growth and metastasis depends on the availability of energy. Energy-sensing systems are critical in maintaining a balance between the energy supply and utilization of energy for tumor growth. A central regulator in this process is AMP-activated protein kinase (AMPK). In times of energy deficit, AMPK is allosterically modified by the binding of increased levels of AMP and ADP, making it a target of specific AMPK kinases (AMPKKs). AMPK signaling prompts cells to produce energy at the expense of growth and motility, opposing the actions of insulin and growth factors...
2017: American Journal of Translational Research
https://www.readbyqxmd.com/read/28336918/clinically-applicable-gaba-receptor-positive-allosteric-modulators-promote-%C3%A3-cell-replication
#6
Jide Tian, Hoa Dang, Blake Middleton, Daniel L Kaufman
A key goal of diabetes research is to develop treatments to safely promote human ß-cell replication. It has recently become appreciated that activation of γ-aminobutyric acid receptors (GABA-Rs) on ß-cells can promote their survival and replication. A number of positive allosteric modulators (PAMs) that enhance GABA's actions on neuronal GABAA-Rs are in clinical use. Repurposing these GABAA-R PAMs to help treat diabetes is theoretically appealing because of their safety and potential to enhance the ability of GABA, secreted from ß-cells, or exogenously administered, to promote ß-cell replication and survival...
March 23, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28336831/-calcilytic-drugs-feature-and-future
#7
Itsuro Endo
Calcium-sensing receptor(CaSR)is highly expressed in parathyroid, kidney, bone, and small and large intestines to regulate Ca homeostasis. Calcilytics are allosteric antagonists of CaSR, and stimulate endogenous PTH release. Several calcilytics have been evaluated as anabolic therapies for postmenopausal osteoporosis but clinical development of all of them has been abandoned because the lacked clinical efficacy. Calcilytics might be repurposed for new indications like autosomal dominant hypocalcemia or other disorders...
2017: Clinical Calcium
https://www.readbyqxmd.com/read/28336830/-the-discovery-research-and-development-of-etelcalcetide-hydrochloride-the-world-1st-intravenous-calcimimetics
#8
Atsuto Inoue, Kazutsune Harada
Etelcalcetide hydrochloride is the first intravenous calcimimetics agent for secondary hyperparathyroidism (SHPT). Etelcalcetide hydrochloride is to be administered through dialysis circuit by physician or medical staff upon completion of dialysis and such administration is expected to reduce the burden of medication in patients. From the nonclinical study results, etelcalcetide functions as an allosteric activator of calcium-sensing receptor(CaSR). Etelcalcetide suppressed PTH secretion both in vitro and in vivo...
2017: Clinical Calcium
https://www.readbyqxmd.com/read/28336323/m1-muscarinic-activation-induces-long-lasting-increase-in-intrinsic-excitability-of-striatal-projection-neurons
#9
Xiaohui Lv, Jonathan W Dickerson, Jerri M Rook, Craig W Lindsley, P Jeffrey Conn, Zixiu Xiang
The dorsolateral striatum is critically involved in movement control and motor learning. Striatal function is regulated by a variety of neuromodulators including acetylcholine. Previous studies have shown that cholinergic activation excites striatal principal projection neurons, medium spiny neurons (MSNs), and this action is mediated by muscarinic acetylcholine subtype 1 receptors (M1) through modulating multiple potassium channels. In the present study, we used electrophysiology techniques in conjunction with optogenetic and pharmacological tools to determine the long-term effects of striatal cholinergic activation on MSN intrinsic excitability...
March 20, 2017: Neuropharmacology
https://www.readbyqxmd.com/read/28336274/characterization-molecular-docking-dynamics-simulation-and-metadynamics-of-kisspeptin-receptor-with-kisspeptin
#10
Mohd Ashraf Rather, Syed Hussain Basha, Irfan Ahmad Bhat, Niti Sharma, Priyanka Nandanpawar, Mohan Badhe, Gireesh-Babu P, Aparna Chaudhari, Jitendra Kumar Sundaray, Rupam Sharma
We report molecular characterization of the kisspeptin receptor (kiss1r), an essential gatekeeper for reproduction and onset of puberty in vertebrates. The full-length cDNA sequence of kiss1r is 1786bp which consist of 5' UTR (untranslated region) 261bp, 3' UTR of 424bp and open reading frame of 1101 encoding a putative protein of 366 amino acids. Basal tissue expression pattern of kiss1r mRNA revealed that it is mainly expressed in the brain and testis. We also report the structure of the kiss1r, along with plausible activation mechanism of this receptor by kisspeptin using computational modelling and dynamic simulation approach of multiple 100ns of timescale...
March 20, 2017: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/28335551/molecular-basis-for-modulation-of-metabotropic-glutamate-receptors-and-their-drug-actions-by-extracellular-ca-2
#11
REVIEW
Juan Zou, Jason Y Jiang, Jenny J Yang
Metabotropic glutamate receptors (mGluRs) associated with the slow phase of the glutamatergic signaling pathway in neurons of the central nervous system have gained importance as drug targets for chronic neurodegenerative diseases. While extracellular Ca(2+) was reported to exhibit direct activation and modulation via an allosteric site, the identification of those binding sites was challenged by weak binding. Herein, we review the discovery of extracellular Ca(2+) in regulation of mGluRs, summarize the recent developments in probing Ca(2+) binding and its co-regulation of the receptor based on structural and biochemical analysis, and discuss the molecular basis for Ca(2+) to regulate various classes of drug action as well as its importance as an allosteric modulator in mGluRs...
March 21, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28332150/dynamic-nature-of-presenilin1-%C3%AE-secretase-implication-for-alzheimer-s-disease-pathogenesis
#12
REVIEW
Katarzyna Marta Zoltowska, Oksana Berezovska
Presenilin 1 (PS1) is a catalytic component of the γ-secretase complex, responsible for the intramembraneous cleavage of more than 90 type I transmembrane proteins, including Alzheimer's disease (AD)-related amyloid precursor protein (APP). The γ-secretase-mediated cleavage of the APP C-terminal membrane stub leads to the production of various amyloid β (Aβ) species. The assembly of Aβ into neurotoxic oligomers, which causes synaptic dysfunction and neurodegeneration, is influenced by the relative ratio of the longer (Aβ42/43) to shorter Aβ (Aβ40) peptides...
March 22, 2017: Molecular Neurobiology
https://www.readbyqxmd.com/read/28329763/the-allosteric-inhibitor-abl001-enables-dual-targeting-of-bcr-abl1
#13
Andrew A Wylie, Joseph Schoepfer, Wolfgang Jahnke, Sandra W Cowan-Jacob, Alice Loo, Pascal Furet, Andreas L Marzinzik, Xavier Pelle, Jerry Donovan, Wenjing Zhu, Silvia Buonamici, A Quamrul Hassan, Franco Lombardo, Varsha Iyer, Michael Palmer, Giuliano Berellini, Stephanie Dodd, Sanjeev Thohan, Hans Bitter, Susan Branford, David M Ross, Timothy P Hughes, Lilli Petruzzelli, K Gary Vanasse, Markus Warmuth, Francesco Hofmann, Nicholas J Keen, William R Sellers
Chronic myeloid leukaemia (CML) is driven by the activity of the BCR-ABL1 fusion oncoprotein. ABL1 kinase inhibitors have improved the clinical outcomes for patients with CML, with over 80% of patients treated with imatinib surviving for more than 10 years. Second-generation ABL1 kinase inhibitors induce more potent molecular responses in both previously untreated and imatinib-resistant patients with CML. Studies in patients with chronic-phase CML have shown that around 50% of patients who achieve and maintain undetectable BCR-ABL1 transcript levels for at least 2 years remain disease-free after the withdrawal of treatment...
March 22, 2017: Nature
https://www.readbyqxmd.com/read/28328743/acetylcholine-atropine-interactions-paradoxical-effects-on-atrial-fibrillation-inducibility
#14
Yu Liu, Benjamin J Scherlag, Youqi Fan, Wenfang Xia, He Huang, Sunny S Po
Atropine (ATr) is well known as a cholinergic antagonist, however, at low concentrations ATr could paradoxically accentuate the parasympathetic actions of acetylcholine (ACh). In 22 pentobarbital anesthetized dogs, via a left and right thoracotomy, a leak proof barrier was attached to isolate the atrial appendages (AAs) from the rest of the atria. In Group 1(Ach+ATr+Ach), ACh, 100 mM, was placed on the AA followed by the application of ATr, 2mg/cc. The average AFdur was 17±7 minutes. After ATr was applied to the AA and ACh again tested, the AFdur was markedly attenuated (2±2 minutes, p<0...
March 21, 2017: Journal of Cardiovascular Pharmacology
https://www.readbyqxmd.com/read/28327612/endogenous-opioids-regulate-moment-to-moment-neuronal-communication-and-excitability
#15
Bryony L Winters, Gabrielle C Gregoriou, Sarah A Kissiwaa, Oliver A Wells, Danashi I Medagoda, Sam M Hermes, Neil T Burford, Andrew Alt, Sue A Aicher, Elena E Bagley
Fear and emotional learning are modulated by endogenous opioids but the cellular basis for this is unknown. The intercalated cells (ITCs) gate amygdala output and thus regulate the fear response. Here we find endogenous opioids are released by synaptic stimulation to act via two distinct mechanisms within the main ITC cluster. Endogenously released opioids inhibit glutamate release through the δ-opioid receptor (DOR), an effect potentiated by a DOR-positive allosteric modulator. Postsynaptically, the opioids activate a potassium conductance through the μ-opioid receptor (MOR), suggesting for the first time that endogenously released opioids directly regulate neuronal excitability...
March 22, 2017: Nature Communications
https://www.readbyqxmd.com/read/28327441/structure-based-design-synthesis-and-biological-evaluation-of-amino-phosphonate-derivatives-as-human-glucokinase-activators
#16
Nanda Kumar Yellapu, Ravendra Babu Kilaru, Nagaraju Chamarthi, Sarma Pvgk, Bhaskar Matcha
Glucokinase (GK) is a potential therapeutic target of type 2 diabetes and GK activators (GKAs) represent a promising class of small organic molecules which enhance GK activity. Based on the configuration and conformation of the allosteric site of GK, we have designed a novel class of amino phosphonate derivatives in order to develop potent GKAs. The QSAR model developed using numerous descriptors revealed its potential with the best effective statistical values of RMSE=1.52 and r(2)=0.30. Moreover, application of this model on the present test set GKAs proved to be worthy to predict their activities as a better linear relationship was observed with RMSE=0...
March 2, 2017: Computational Biology and Chemistry
https://www.readbyqxmd.com/read/28326772/illuminating-the-reaction-pathways-of-viromimetic-assembly
#17
Hande E Cingil, Emre B Boz, Giovanni Biondaro, Renko de Vries, Martien A Cohen Stuart, Daniela J Kraft, Paul van der Schoot, Joris Sprakel
The co-assembly of well-defined biological nanostructures relies on a delicate balance between attractive and repulsive interactions between biomolecular building blocks. Viral capsids are a prototypical example, where coat proteins exhibit not only self-interactions but also interact with the cargo they encapsulate. In Nature the balance between antagonistic and synergistic interactions is evolved to avoid kinetic trapping and polymorphism. To date it has remained a major challenge to experimentally disentangle the complex kinetic reaction pathways that underlie successful co-assembly of biomolecular building blocks in a non-invasive approach with high temporal resolution...
March 22, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28325873/priming-gpcr-signaling-through-the-synergistic-effect-of-two-g-proteins
#18
Tejas M Gupte, Rabia U Malik, Ruth F Sommese, Michael Ritt, Sivaraj Sivaramakrishnan
Although individual G-protein-coupled receptors (GPCRs) are known to activate one or more G proteins, the GPCR-G-protein interaction is viewed as a bimolecular event involving the formation of a ternary ligand-GPCR-G-protein complex. Here, we present evidence that individual GPCR-G-protein interactions can reinforce each other to enhance signaling through canonical downstream second messengers, a phenomenon we term "GPCR priming." Specifically, we find that the presence of noncognate Gq protein enhances cAMP stimulated by two Gs-coupled receptors, β2-adrenergic receptor (β2-AR) and D1 dopamine receptor (D1-R)...
March 21, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28324160/regulation-of-blood-oxygen-transport-in-hibernating-mammals
#19
Inge G Revsbech, Angela Fago
Along with the periodic reductions in O2 requirements of mammalian hibernators during winter, the O2 affinity of the blood of mammalian hibernators is seasonally regulated to help match O2 supply to consumption, contributing to limit tissue oxidative stress, particularly at arousals. Specifically, mammalian hibernators consistently show an overall increase in the blood-O2 affinity, which causes a decreased O2 unloading to tissues, while having similar or lower tissue O2 tensions during hibernation. This overview explores how the decreased body temperature and concentration of red blood cell 2,3-diphosphoglycerate (DPG) that occur in hibernation contribute separately or in combination to the concurrent increase in the O2 affinity of the hemoglobin, the O2 carrier protein of the blood...
March 21, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28323850/ligand-guided-homology-modelling-of-the-gabab2-subunit-of-the-gabab-receptor
#20
Thibaud Freyd, Dawid Warszycki, Stefan Mordalski, Andrzej J Bojarski, Ingebrigt Sylte, Mari Gabrielsen
γ-aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the central nervous system, and disturbances in the GABAergic system have been implicated in numerous neurological and neuropsychiatric diseases. The GABAB receptor is a heterodimeric class C G protein-coupled receptor (GPCR) consisting of GABAB1a/b and GABAB2 subunits. Two GABAB receptor ligand binding sites have been described, namely the orthosteric GABA binding site located in the extracellular GABAB1 Venus fly trap domain and the allosteric binding site found in the GABAB2 transmembrane domain...
2017: PloS One
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