scholarly journals Analysis of Porphyra Membrane Transporters Demonstrates Gene Transfer among Photosynthetic Eukaryotes and Numerous Sodium-Coupled Transport Systems

2012 ◽  
Vol 158 (4) ◽  
pp. 2001-2012 ◽  
Author(s):  
Cheong Xin Chan ◽  
Simone Zäuner ◽  
Glen Wheeler ◽  
Arthur R. Grossman ◽  
Simon E. Prochnik ◽  
...  
Keyword(s):  
Gene Transfer ◽  
Membrane Transporters ◽  
Transport Systems ◽  
Coupled Transport ◽  
Photosynthetic Eukaryotes ◽  
Sodium Coupled Transport

Approach to the patient with salt-wasting tubulopathies

2018 ◽  
Author(s):  
Detlef Bockenhauer ◽  
Robert Kleta
Keyword(s):  
Sodium Concentration ◽  
Systemic Blood Pressure ◽  
Transport Systems ◽  
Sodium Reabsorption ◽  
Coupled Transport ◽  
Salt Diet ◽  
Salt Wasting ◽  
Low Salt ◽  
Sodium Coupled Transport ◽  
Parallel Action

Sodium is the main ion of the extracellular compartments, and it is through control of sodium reabsorption that the kidneys maintain volume homoeostasis and systemic blood pressure. The amount of sodium that is first filtered by the glomerulus and then reabsorbed in the tubule is quite staggering: assuming a glomerular filtration rate of 100 mL/min and a serum sodium concentration of 140 mmol/L, an average-sized person filters about 20,000 mmol of sodium per day, equivalent to the amount in 1.2 kg of cooking salt. In the steady state, the amount of sodium excreted is equal to the amount ingested. An average Western diet contains about 8–10 g of salt per day; a low-salt diet may be around 2 g per day. Under physiological conditions, the tubules reabsorb about 99% of filtered sodium. This enormous task is accomplished by a combination of distinct and sequentially oriented sodium or sodium-coupled transport systems along the nephron and the concerted and parallel action of some of these systems within the kidney. These are described, along with the consequences of disorders of the processes. A diagnostic approach to salt-losing states such as Fanconi, Bartter Gitelman and other syndromes, and hypoaldosteronism, is described.

558 Sodium-Coupled Transport of Butyrate By SLC5A8 Mediates Tumor Suppression in the Colon

2008 ◽  
Vol 134 (4) ◽  
pp. A-849
Author(s):  
Gail Cresci ◽  
Muthusamy -. Thangaraju ◽  
Darren Browning ◽  
Vadivel Ganapathy
Keyword(s):  
Tumor Suppression ◽  
Coupled Transport ◽  
Sodium Coupled Transport

scholarly journals Kinetic mechanism of coupled binding in sodium-aspartate symporter GltPh

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
SeCheol Oh ◽  
Olga Boudker
Keyword(s):  
Kinetic Mechanism ◽  
Membrane Transporters ◽  
Cooperative Binding ◽  
Sodium Ions ◽  
Coupled Transport ◽  
Concentration Gradients ◽  
Pyrococcus Horikoshii ◽  
Active Membrane ◽  
Rapid Equilibrium

Many secondary active membrane transporters pump substrates against concentration gradients by coupling their uptake to symport of sodium ions. Symport requires the substrate and ions to be always transported together. Cooperative binding of the solutes is a key mechanism contributing to coupled transport in the sodium and aspartate symporter from Pyrococcus horikoshii GltPh. Here, we describe the kinetic mechanism of coupled binding for GltPh in the inward facing state. The first of the three coupled sodium ions, binds weakly and slowly, enabling the protein to accept the rest of the ions and the substrate. The last ion binds tightly, but is in rapid equilibrium with solution. Its release is required for the complex disassembly. Thus, the first ion serves to ‘open the door’ for the substrate, the last ion ‘locks the door’ once the substrate is in, and one ion contributes to both events.

Oxygen-sensitive membrane transporters in vertebrate red cells

2000 ◽  
Vol 203 (9) ◽  
pp. 1395-1407 ◽  
Author(s):  
J.S. Gibson ◽  
A.R. Cossins ◽  
J.C. Ellory
Keyword(s):  
Membrane Transporters ◽  
Red Cells ◽  
Transport Systems ◽  
Red Cell ◽  
Organic Systems ◽  
Wide Range ◽  
Oxygen Sensitive ◽  
Radical Generation ◽  
Membrane Transport Systems

Oxygen is essential for all higher forms of animal life. It is required for oxidative phosphorylation, which forms the bulk of the energy supply of most animals. In many vertebrates, transport of O(2) from respiratory to other tissues, and of CO(2) in the opposite direction, involves red cells. These are highly specialised, adapted for their respiratory function. Intracellular haemoglobin, carbonic anhydrase and the membrane anion exchanger (AE1) increase the effective O(2)- and CO(2)-carrying capacity of red cells by approximately 100-fold. O(2) also has a pathological role. It is a very reactive species chemically, and oxidation, free radical generation and peroxide formation can be major hazards. Cells that come into contact with potentially damaging levels of O(2) have a variety of systems to protect them against oxidative damage. Those in red cells include catalase, superoxide dismutase and glutathione. In this review, we focus on a third role of O(2), as a regulator of membrane transport systems, a role with important consequences for the homeostasis of the red cell and also the organism as a whole. We show that regulation of red cell transporters by O(2) is widespread throughout the vertebrate kingdom. The effect of O(2) is selective but involves a wide range of transporters, including inorganic and organic systems, and both electroneutral and conductive pathways. Finally, we discuss what is known about the mechanism of the O(2) effect and comment on its physiological and pathological roles.

Actions of thiocyanate and N-phenylmaleimide on volume-responsive Na and K transport in dog red cells

1992 ◽  
Vol 262 (2) ◽  
pp. C418-C421 ◽  
Author(s):  
J. C. Parker ◽  
G. C. Colclasure
Keyword(s):  
Red Blood Cells ◽  
Cell Volume ◽  
Electrophoretic Mobility ◽  
Blood Cells ◽  
Membrane Transporters ◽  
Red Cells ◽  
Transport Systems ◽  
Volume Changes ◽  
Sulfhydryl Reagent ◽  
K Transport

Two sets of observations suggest a linkage between volume-responsive Na and K transport systems in dog red blood cells. 1) The lyotropic anion thiocyanate inhibits shrinkage-induced Na-H exchange and stimulates swelling-induced K-Cl cotransport. 2) The effect of a brief incubation with N-phenylmaleimide (NPM) on Na and K transport depends on the volume of the cells at the time of exposure to the sulfhydryl reagent. Cells shrunken during the NPM incubation and then brought back to normal volume behave as though they were still shrunken, i.e., they show an increased Na flux and a decreased K flux. Cells incubated with NPM in a swollen state retain fluxes characteristic of swollen cells when returned to a normal volume. The electrophoretic mobility of the membrane-associated enzyme glyceraldehyde-3-phosphate dehydrogenase is influenced by the cell volume at the time of NPM exposure. These findings point to the existence of a system in cells that perceives volume changes and coordinates the responses of membrane transporters.

scholarly journals The ECF sigma factor PvdS regulates the type I-F CRISPR-Cas system in Pseudomonas aeruginosa

2020 ◽  
Author(s):  
Stephen Dela Ahator ◽  
Wang Jianhe ◽  
Lian-Hui Zhang
Keyword(s):  
Gene Transfer ◽  
Horizontal Gene Transfer ◽  
Sigma Factor ◽  
Regulatory System ◽  
Stress Factors ◽  
Iron Limitation ◽  
Transport Systems ◽  
Type I ◽  
Ecf Sigma Factor ◽  
Wide Range

AbstractDuring infection, successful colonization of bacteria requires a fine-tuned supply of iron acquired via iron transport systems. However, the transport systems serve as phage attachment sites and entry portals for foreign nucleic acid. Most bacteria possess the CRISPR-Cas system, which targets and destroys foreign nucleic acids and prevents deleterious effects of horizontal gene transfer. To understand the regulation of the CRISPR-Cas system, we performed genome-wide random transposon mutagenesis which led to the identification of the Extracytoplasmic Function (ECF) Sigma factor, PvdS as a regulator of the Type I-F CRISPR-Cas system in P. aeruginosa. We show that under iron-depleted conditions PvdS induces the expression of the type I-F CRISPR-Cas system. This regulatory mechanism involves direct interaction of PvdS with specific binding sites in the promoter region of cas1. Furthermore, activation of the CRISPR-Cas system under iron-depleted conditions increases horizontal gene transfer (HGT) interference and adaptation. The PvdS activation of the CRISPR-Cas system under iron limitation highlights the versatility of the P. aeruginosa in multitasking its regulatory machinery to integrate multiple stress factors.ImportanceP. aeruginosa infects a wide range of host organisms and adapts to various environmental stress factors such as iron limitation due to its elaborate regulatory system. P aeruginosa possesses the type I-F CRISPR-Cas system as a defense mechanism against phages infection and HGT. This work highlights the ability of P. aeruginosa to multitask its iron regulatory system to control the CRISPR-Cas system under a physiologically relevant stress factor such as iron limitation where the bacteria are vulnerable to phage infection. It also adds to the knowledge of the regulation of the CRISPR-Cas system in bacteria and presents a possible target that could prevent the emergence of phage resistance via the CRISPR-Cas system during the development of phage therapy.

Sign in / Sign up

Export Citation Format

Share Document