Search results for "transport systems"
showing 10 items of 33 documents
Activation of L-arginine transport by protein kinase C in rabbit, rat and mouse alveolar macrophages
1998
1 The role of protein kinase C in controlling L-arginine transport in alveolar macrophages was investigated. 2 L-[3H]Arginine uptake in rabbit alveolar macrophages declined by 80 % after 20 h in culture. 4β-Phorbol 12-myristate 13-acetate (PMA), but not 4α-phorbol 12-myristate 13-acetate (α-PMA), present during 20 h culture, enhanced L-[3H]arginine uptake more than 10-fold. Staurosporine and chelerythrine opposed this effect. 3 L-[3H]Arginine uptake was saturable and blockable by L-lysine. After PMA treatment Vmax was increased more than 5-fold and Km was reduced from 0.65 to 0.32 mM. 4 Time course experiments showed that PMA increased L-[3H]arginine uptake almost maximally within 2 h. This…
Human cationic amino acid transporter hCAT-3 is preferentially expressed in peripheral tissues.
2001
At least five distinct carrier proteins form the family of mammalian cationic amino acid transporters (CATs). We have cloned a cDNA containing the complete coding region of human CAT-3. hCAT-3 is glycosylated and localized to the plasma membrane. Transport studies in Xenopus laevis oocytes revealed that hCAT-3 is selective for cationic L-amino acids and exhibits a maximal transport activity similar to other CAT proteins. The apparent substrate affinity and sensitivity to trans-stimulation of hCAT-3 resembles most closely hCAT-2B. This is in contrast to rat and murine CAT-3 proteins that have been reported to display a very low activity and to be inhibited by neutral and anionic L-amino acid…
Differential cystine and dibasic amino acid handling after loss of function of the amino acid transporter b0,+ AT (Slc7a9) in mice
2013
Cystinuria is an autosomal recessive disease caused by mutations in SLC3A1 ( rBAT) and SLC7A9 ( b 0,+ AT). Gene targeting of the catalytic subunit ( Slc7a9) in mice leads to excessive excretion of cystine, lysine, arginine, and ornithine. Here, we studied this non-type I cystinuria mouse model using gene expression analysis, Western blotting, clearance, and brush-border membrane vesicle (BBMV) uptake experiments to further characterize the renal and intestinal consequences of losing Slc7a9 function. The electrogenic and BBMV flux studies in the intestine suggested that arginine and ornithine are transported via other routes apart from system b0,+. No remarkable gene expression changes were…
Forecasting Adverse Weather Situations in the Road Network
2016
Weather is an important factor that affects traffic flow and road safety. Adverse weather situations affect the driving conditions directly; hence, drivers must be informed about the weather conditions downstream to adapt their driving. In the framework of intelligent transport systems, several systems have been developed to know the weather situations and inform drivers. However, these systems do not forecast weather in advance, and they need the support of road operators to inform drivers. This paper presents a new autonomous system to forecast weather conditions in a short time and to give users the information obtained. The system uses a set of algorithms and rules to determine the weat…
Intracellular accumulation of l-Arg, kinetics of transport, and potassium leak conductance in oocytes from Xenopus laevis expressing hCAT-1, hCAT-2A,…
2004
AbstractCationic amino acid transporters play an important role in the intracellular supply of l-Arg and the generation of nitric oxide. Since the transport of l-Arg is voltage-dependent, we aimed at determining the intracellular l-Arg concentration and describing the transport of l-Arg in terms of Michaelis–Menten kinetics, taking into account membrane voltage. The human isoforms of the cationic amino acid transporters, hCAT-1, hCAT-2A, and hCAT-2B, were expressed in oocytes from Xenopus laevis and studied with the voltage clamp technique and in tracer experiments. We found that l-Arg was concentrated intracellularly by all hCAT isoforms and that influx and efflux, in the steady state of e…
Na+ -dependent neutral amino acid transporters A, ASC, and N of the blood-brain barrier: mechanisms for neutral amino acid removal.
2004
Four Na+-dependent transporters of neutral amino acids (NAA) are known to exist in the abluminal membranes (brain side) of the blood-brain barrier (BBB). This article describes the kinetic characteristics of systems A, ASC, and N that, together with the recently described Na+-dependent system for large NAA (Na+-LNAA), provide a basis for understanding the functional organization of the BBB. The data demonstrate that system A is voltage dependent (3 positive charges accompany each molecule of substrate). Systems ASC and N are not voltage dependent. Each NAA is a putative substrate for at least one system, and several NAA are transported by as many as three. System A transports Pro, Ala, His,…
Btn2p is involved in ethanol tolerance and biofilm formation in flor yeast
2008
Flor yeasts are a particular kind of Saccharomyces cerevisiae strains involved in Sherry wine biological ageing. During this process, yeasts form a film on the wine surface and use ethanol as a carbon source, producing acetaldehyde as a by-product. Acetaldehyde induces BTN2 transcription in laboratory strains. Btn2p is involved in the control of the subcellular localization of different proteins. The BTN2 gene shows a complex expression pattern in wine yeast, increasing its expression by acetaldehyde, but repressing it by ethanol. A flor yeast strain transcribes more BTN2 than a first fermentation yeast during growth, but less under different stress conditions. BTN2 deletion decreases flor …
Between the Megalopolis and the Deep Blue Sky: Challenges of Transport with UAVs in Future Smart Cities
2019
International audience; With the rapid increase of the world's urban population, the infrastructure of the constantly expanding metropolitan areas is undergoing an immense pressure. To meet the growing demands of sustainable urban environments and improve the quality of life for citizens, municipalities will increasingly rely on novel transport solutions. In particular, Unmanned Aerial Vehicles (UAVs) are expected to have a crucial role in the future smart cities thanks to their interesting features such as autonomy, flexibility, mobility, adaptive altitude, and small dimensions. However, densely populated megalopolises of the future are administrated by several municipals, governmental and…
Expression, regulation and function of carrier proteins for cationic amino acids.
2001
Different carrier proteins exhibiting distinct transport properties participate in cationic amino acid transport. There are sodium-independent systems, such as b+, y+, y+L and b0,+, and a sodium-dependent system B0,+, most of which have now been identified at the molecular level. In most non-epithelial cells, members of the cationic amino acid transporter (CAT) family mediating system y+ activity seem to be the major entry pathway for cationic amino acids. CAT proteins underlie complex regulation at the transcriptional, post-transcriptional and activity levels. Recent evidence indicates that individual CAT isoforms are necessary for providing the substrate for nitric oxide synthesis, for ex…
Plasma membrane transporters for arginine
2004
The supply of arginine may become rate limiting for enzymatic reactions that use this semiessential amino acid as a substrate (e.g., nitric oxide, agmatine, creatine, and urea synthesis), particularly under conditions of high demand such as growth, sepsis, or wound healing. In addition, arginine acts as a signaling molecule that regulates essential cellular functions such as protein synthesis, apoptosis, and growth. In the past decade, a number of carrier proteins for amino acids have been identified on the molecular level. They belong to different gene families, exhibit overlapping but distinctive substrate specificities, and can further be distinguished by their requirement for the cotran…