Search results for "Antiporter"
showing 10 items of 31 documents
The CFTR associated protein CAP70 interacts with the apical Cl-/HCO3- exchanger DRA in rabbit small intestinal mucosa.
2005
DRA (down regulated in adenoma) is an intestinal anion exchanger, acting in parallel with NHE3 to facilitate ileal and colonic NaCl absorption. Furthermore it is involved in small intestinal bicarbonate secretion. Because DRA has a PDZ interaction motif, which may influence its properties, we searched for DRA-interacting PDZ adapter proteins in the small intestine. Using an overlay assay with the recombinant DRA C-terminus as a ligand, a 70 kDa protein was labeled, which was restricted to the brush border membrane in rabbit duodenal and ileal mucosa and was not detected in the colon. Destruction of the C-terminal PDZ interaction motif abolished this band, suggesting a specific protein-prote…
The plasma membrane channel ORAI1 mediates detrimental calcium influx caused by endogenous oxidative stress.
2013
The mouse hippocampal cell line HT22 is an excellent model for studying the consequences of endogenous oxidative stress. Addition of extracellular glutamate depletes the cells of glutathione (GSH) by blocking the glutamate-cystine antiporter system x(c)(-). GSH is the main antioxidant in neurons and its depletion induces a well-defined program of cell death called oxytosis, which is probably synonymous with the iron-dependent form of non-apoptotic cell death termed ferroptosis. Oxytosis is characterized by an increase of reactive oxygen species and a strong calcium influx preceding cell death. We found a significant reduction in store-operated calcium entry (SOCE) in glutamate-resistant HT2…
Calcium signatures and signaling in cytosol and organelles of tobacco cells induced by plant defense elicitors
2011
Calcium signatures induced by two elicitors of plant defense reactions, namely cryptogein and oligogalacturonides, were monitored at the subcellular level, using apoaequorin-transformed Nicotiana tabacum var Xanthi cells, in which the apoaequorin calcium sensor was targeted either to cytosol, mitochondria or chloroplasts. Our study showed that both elicitors induced specific Ca2+ signatures in each compartment, with the most striking difference relying on duration. Common properties also emerged from the analysis of Ca2+ signatures: both elicitors induced a biphasic cytosolic [Ca2+] elevation together with a single mitochondrial [Ca2+] elevation concomitant with the first cytosolic [Ca2+] p…
Differential salinity-induced variations in the activity of H+-pumps and Na+/H+ antiporters that are involved in cytoplasm ion homeostasis as a funct…
2011
The characterisation of cellular responses to salinity in staple crops is necessary for the reliable identification of physiological markers of salinity tolerance. Under saline conditions, variations in proton gradients that are generated by membrane-bound H⁺ pumps are crucial for maintaining cytoplasm homeostasis. We examined short (15 h) and longer term effects (4 days) of NaCl stress on the H⁺ pumping activities that are associated with the plasma membrane (P-ATPase) and the tonoplast (V-ATPase and V-PPase) in rice (Oryza sativa L.) callus lines that displayed different levels of NaCl tolerance and were established from two japonica rice cultivars. The applied stress conditions were base…
The sensor kinase DcuS of Escherichia coli: two stimulus input sites and a merged signal pathway in the DctA/DcuS sensor unit
2012
Abstract The membrane-integral sensor kinase DcuS of Escherichia coli consists of a periplasmically located sensory PASP domain, transmembrane helices TM1 and TM2, a cytoplasmic PASC domain and the kinase domain. Stimulus (C4-dicarboxylate) binding at PASP is required to stimulate phosphorylation of the kinase domain, resulting in phosphoryl transfer to the response regulator DcuR. PASC functions as a signaling device or a relay in signal transfer from TM2 to the kinase. Phosphorylated DcuR induces the expression of the target genes. Sensing by DcuS requires the presence of the C4-dicarboxylate transporter DctA during aerobic growth. DctA forms a sensor unit with DcuS, and a short C-termina…
Chloride, carboxylate and carbonate transport by ortho-phenylenediamine-based bisureas
2013
Highly potent but structurally simple transmembrane anion transporters are reported that function at receptor to lipid ratios as low as 1 : 1 000 000. The compounds, based on the simple ortho-phenylenediamine-based bisurea scaffold, have been studied for their ability to facilitate chloride/nitrate and chloride/bicarbonate antiport, and HCl symport processes using a combination of ion selective electrode and fluorescence techniques. In addition, the transmembrane transport of dicarboxylate anions (maleate and fumarate) by the compounds was examined. Molecular dynamics simulations showed that these compounds permeate the membrane more easily than other promising receptors corroborating the e…
DcuA of aerobically grownEscherichia coliserves as a nitrogen shuttle (L‐aspartate/fumarate) for nitrogen uptake
2018
DcuA of Escherichia coli is known as an alternative C4 -dicarboxylate transporter for the main anaerobic C4 -dicarboxylate transporter DcuB. Since dcuA is expressed constitutively under aerobic and anaerobic conditions, DcuA was suggested to serve aerobically as a backup for the aerobic (DctA) transporter, or for the anabolic uptake of C4 -dicarboxylates. In this work, it is shown that DcuA is required for aerobic growth with L-aspartate as a nitrogen source, whereas for growth with L-aspartate as a carbon source, DctA was needed. Strains with DcuA catalyzed L-aspartate and C4 -dicarboxylate uptake (like DctA), or an L-aspartate/C4 -dicarboxylate antiport (unlike DctA). DcuA preferred L-asp…
Fumarate regulation of gene expression in Escherichia coli by the DcuSR (dcuSR genes) two-component regulatory system.
1998
ABSTRACT In Escherichia coli the genes encoding the anaerobic fumarate respiratory system are transcriptionally regulated by C 4 -dicarboxylates. The regulation is effected by a two-component regulatory system, DcuSR, consisting of a sensory histidine kinase (DcuS) and a response regulator (DcuR). DcuS and DcuR are encoded by the dcuSR genes (previously yjdHG ) at 93.7 min on the calculated E. coli map. Inactivation of the dcuR and dcuS genes caused the loss of C 4 -dicarboxylate-stimulated synthesis of fumarate reductase ( frdABCD genes) and of the anaerobic fumarate-succinate antiporter DcuB ( dcuB gene). DcuS is predicted to contain a large periplasmic domain as the supposed site for C 4…
Glial ion transport and volume control.
1991
K(+)-induced glial swelling results from an intricate interaction of transport and diffusion processes and metabolic stimulation, with many open questions remaining. Our concept of the major mechanisms involved can be summarized as follows: high extracellular K+ causes a burst-like stimulation of Na+/K+ ATPase and, hence, increases the metabolic demands. Lactate is produced; the cell is slightly acidified. To maintain a normal intracellular pH, the Na+/K+ antiporter extrudes protons and supplies Na+ for further Na+/K+ exchange. In addition, K+ ions enter the cell via membrane channels or furosemide-inhibitable transport. K+, Cl-, and lactate- ions accumulate as the osmotic basis for cell sw…
De Novo Mutations in SLC25A24 Cause a Disorder Characterized by Early Aging, Bone Dysplasia, Characteristic Face, and Early Demise
2017
International audience; A series of simplex cases have been reported under various diagnoses sharing early aging, especially evident in congenitally decreased subcutaneous fat tissue and sparse hair, bone dysplasia of the skull and fingers, a distinctive facial gestalt, and prenatal and postnatal growth retardation. For historical reasons, we suggest naming the entity Fontaine syndrome. Exome sequencing of four unrelated affected individuals showed that all carried the de novo missense variant c.649C>T (p.Arg217Cys) or c.650G>A (p.Arg217His) in SLC25A24, a solute carrier 25 family member coding for calcium-binding mitochondrial carrier protein (SCaMC-1, also known as SLC25A24). SLC25A24 all…