scholarly journals Active transport of GSSG from reconstituted erythrocyte ghosts

Blood ◽  
1975 ◽  
Vol 46 (1) ◽  
pp. 111-117 ◽  
Author(s):  
J Prchal ◽  
SK Srivastava ◽  
E Beutler
Keyword(s):  
Active Transport ◽  
Transport System ◽  
Concentration Gradient ◽  
Human Erythrocyte ◽  
Red Cells ◽  
Intracellular Concentration ◽  
Maximal Velocity ◽  
Erythrocyte Ghosts ◽  
The Relationship

Abstract Human erythrocyte ghosts were loaded with 35S-labeled GSSG and with a sucrose marker, and the transport of GSSG to the suspending medium was studied. GSSG transport from ghosts occurred only when ATP was also present in the ghosts, proceeded against a concentration gradient, and was inhibited by fluoride. The rate of transport was dependent upon the intracellular concentration of GSSG. The relationship between GSSG concentration and rate of transport was sigmoidal. Half-maximal transport was observed at a GSSG concentration of approximately 9.6mM. The maximal velocity was estimated to be in the range of 0.27 umole GSSG per ml of ghosts per hr. These data suggest that the rate of GSSG transport a physiologic concentrations of GSSG is not sufficiently rapid to account for the turnover of glutathione by red cells. It seems more likely that the GSSG transport system serves an emergency function of erythrocytes.

scholarly journals Active transport of GSSG from reconstituted erythrocyte ghosts

Blood ◽  
1975 ◽  
Vol 46 (1) ◽  
pp. 111-117
Author(s):  
J Prchal ◽  
SK Srivastava ◽  
E Beutler
Keyword(s):  
Active Transport ◽  
Transport System ◽  
Concentration Gradient ◽  
Human Erythrocyte ◽  
Red Cells ◽  
Intracellular Concentration ◽  
Maximal Velocity ◽  
Erythrocyte Ghosts ◽  
The Relationship

Human erythrocyte ghosts were loaded with 35S-labeled GSSG and with a sucrose marker, and the transport of GSSG to the suspending medium was studied. GSSG transport from ghosts occurred only when ATP was also present in the ghosts, proceeded against a concentration gradient, and was inhibited by fluoride. The rate of transport was dependent upon the intracellular concentration of GSSG. The relationship between GSSG concentration and rate of transport was sigmoidal. Half-maximal transport was observed at a GSSG concentration of approximately 9.6mM. The maximal velocity was estimated to be in the range of 0.27 umole GSSG per ml of ghosts per hr. These data suggest that the rate of GSSG transport a physiologic concentrations of GSSG is not sufficiently rapid to account for the turnover of glutathione by red cells. It seems more likely that the GSSG transport system serves an emergency function of erythrocytes.

Lead and calcium transport in human erythrocyte

1999 ◽  
Vol 18 (5) ◽  
pp. 327-332 ◽  
Author(s):  
J V Calderón-Salinas ◽  
M A Quintanar-Escorcia ◽  
M T González-Martínez ◽  
C E Hernández-Luna
Keyword(s):  
Transport System ◽  
Human Erythrocyte ◽  
Calcium Transport ◽  
Human Erythrocytes ◽  
The Other ◽  
Erythrocyte Ghosts ◽  
Passive Transport ◽  
Ca Uptake

In this paper we report the lead (Pb) and calcium (Ca) uptake by erythrocyte ghosts. In both cases the transport was carried out by a passive transport system with two kinetic components (Michaelis-Menten and Hill). Pb and Ca were capable of inhibiting the transport of the other metal in a non-competitive way. Under hyperpolarization, the uptakes of Ca and Pb were enhanced and the Michaelis-Menten component prevailed. Both Ca and Pb uptakes were inhibited by N-ethyl-maleimide to the same extent. These results indicate that Pb and Ca share the same permeability pathway in human erythrocytes and that this transport system is electrogenic.

scholarly journals Reconstitution of the Ca2+-transport system of human erythrocytes

1980 ◽  
Vol 188 (1) ◽  
pp. 47-54 ◽  
Author(s):  
K Gietzen ◽  
S Seiler ◽  
S Fleischer ◽  
H U Wolf
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Transport System ◽  
Human Erythrocyte ◽  
Room Temperature ◽  
Proteinase Inhibitors ◽  
Membrane Vesicles ◽  
Tween 20 ◽  
Erythrocyte Ghosts ◽  
Lipid Ratio

The (Ca2+ + Mg2+)-dependent ATPase of human erythrocyte ‘ghosts’ was solubilized and reconstituted to form membranous vesicles capable of energized Ca2+ accumulation. The erythrocyte ‘ghosts’ for this purpose were prepared by using isoosmotic freeze-haemolysis in the presence of Tween 20 and proteinase inhibitors to stabilize the preparation. The reconstitution procedure is similar to that developed by Meissner & Fleischer [(1974) J. Biol. Chem. 249, 302-309] for skeletal-muscle sarcoplasmic-reticulum in that: (1) deoxycholate is used for the solubilization of the membrane; (2) controlled dialysis at near room temperature, rather than 0 degree C, is required in order to obtain a functional preparation capable of Ca2+ accumulation; and (3) membrane vesicles can be reassembled with protein/lipid ratio (approx. 60% protein and 40% lipid) similar to that of the original membrane.

scholarly journals Functional reconstitution of Ral-binding GTPase activating protein, RLIP76, in proteoliposomes catalyzing ATP-dependent transport of glutathione conjugate of 4-hydroxynonenal.

2002 ◽  
Vol 49 (3) ◽  
pp. 693-701 ◽  
Author(s):  
Rajendra Sharma ◽  
Abha Sharma ◽  
Yusong Yang ◽  
Sanjay Awasthi ◽  
Sharad S Singhal ◽  
...  
Keyword(s):  
Active Transport ◽  
Concentration Gradient ◽  
Intracellular Concentration ◽  
Gtpase Activating Protein ◽  
Glutathione Conjugate ◽  
Glutathione Conjugates ◽  
Dependent Transport

Earlier studies from our laboratories have shown that RLIP76, a previously described Ral-binding GTPase activating protein (Jullien-Flores et al., 1995, J. Biol. Chem. 270: 22473), is identical with the xenobiotic transporter DNP-SG ATPase, and can catalyze ATP-dependent transport of glutathione-conjugates as well as doxorubin (Awasthi et al., 2000, Biochemistry, 39: 9327). We have now reconstituted purified bacterially expressed RLIP76 in proteoliposomes, and have studied ATP-dependent uptake of the glutathione conjugate of 4-hydroxynonenal (GS-HNE) by these vesicles. Results of these studies show that RLIP76 reconstituted in proteoliposomes catalyzes ATP-dependent transport of GS-HNE against a concentration gradient. The transport of GS-HNE is saturable with respect to ATP as well as GS-HNE with K(m) values of 1.4mM and 2.5 microM, respectively. These studies demonstrate that RLIP76 mediates active transport of GS-HNE, and are consistent with our previous work showing that RLIP76-mediated efflux of GS-HNE regulates the intracellular concentration of 4-HNE and thereby affects 4-HNE mediated signaling.

On the structural organization of biological pumps and channels

1984 ◽  
Vol 42 ◽  
pp. 138-141
Author(s):  
G. Zampighi ◽  
M. Kreman
Keyword(s):  
Active Transport ◽  
Transport System ◽  
Plasma Membranes ◽  
Transport Proteins ◽  
Molecular Organization ◽  
Passive Transport ◽  
Concentration Gradients ◽  
Cell Functions ◽  
Natural Concentration ◽  
Active Transport System

The plasma membranes of most animal cells contain transport proteins which function to provide passageways for the transported species across essentially impermeable lipid bilayers. The channel is a passive transport system which allows the movement of ions and low molecular weight molecules along their concentration gradients. The pump is an active transport system and can translocate cations against their natural concentration gradients. The actions and interplay of these two kinds of transport proteins control crucial cell functions such as active transport, excitability and cell communication. In this paper, we will describe and compare several features of the molecular organization of pumps and channels. As an example of an active transport system, we will discuss the structure of the sodium and potassium ion-activated triphosphatase [(Na+ +K+)-ATPase] and as an example of a passive transport system, the communicating channel of gap junctions and lens junctions.

scholarly journals Implications of Autonomous Vehicles for Accessibility and Transport Equity: A Framework Based on Literature

2021 ◽  
Vol 13 (8) ◽  
pp. 4448
Author(s):  
Alberto Dianin ◽  
Elisa Ravazzoli ◽  
Georg Hauger
Keyword(s):  
Conceptual Model ◽  
Transport System ◽  
Urban Areas ◽  
Autonomous Vehicles ◽  
Scientific Literature ◽  
Social Groups ◽  
Future Studies ◽  
Social Accessibility ◽  
The Relationship

Increasing accessibility and balancing its distribution across space and social groups are two fundamental goals to make transport more sustainable and equitable. In the next decades, autonomous vehicles (AVs) could significantly transform the transport system, influencing accessibility and transport equity. In particular, depending on the assumed features of AVs (e.g., private or collective) and the considered spatial, social, and regulative context (e.g., rural or urban areas), impacts may be very different. Nevertheless, research in this field is still limited, and the relationship between AV assumptions and accessibility impacts is still partially unclear. This paper aims to provide a framework of the key and emerging aspects related to the implications of AVs for accessibility and transport equity. To set this framework, we perform an analysis of the scientific literature based on a conceptual model describing the implications of AVs for the distribution of accessibility across space and social groups. We recognize four main expected impacts of AVs on accessibility: (1) accessibility polarization, (2) accessibility sprawl, (3) exacerbation of social accessibility inequities, and (4) alleviation of social accessibility inequities. These impacts are described and analyzed in relation to the main AV assumptions expected to trigger them through different mechanisms. Based on the results, some recommendations for future studies intending to focus on the relation between AVs, accessibility, and transport equity are provided.

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