Normal amino acid uptake by cultured human fibroblasts does not require gamma-glutamyl transpeptidase

1976 ◽  
Vol 73 (4) ◽  
pp. 997-1002 ◽  
Author(s):  
Francoise Pellefigue ◽  
Jean DeBrohun Butler ◽  
Stephen P. Spielberg ◽  
Morley D. Hollenberg ◽  
Stephen I. Goodman ◽  
...  
Keyword(s):  
Amino Acid ◽  
Human Fibroblasts ◽  
Amino Acid Uptake ◽  
Acid Uptake ◽  
Gamma Glutamyl Transpeptidase ◽  
Gamma Glutamyl ◽  
Cultured Human Fibroblasts ◽  
Glutamyl Transpeptidase

scholarly journals Energization of amino acid uptake by system A in cultured human fibroblasts

1991 ◽  
Vol 266 (3) ◽  
pp. 1591-1596
Author(s):  
V Dall'Asta ◽  
O Bussolati ◽  
G G Guidotti ◽  
G C Gazzola
Keyword(s):  
Amino Acid ◽  
Human Fibroblasts ◽  
Amino Acid Uptake ◽  
Acid Uptake ◽  
System A ◽  
Cultured Human Fibroblasts

scholarly journals Evidence that cycloleucine affects the high-affinity systems of amino acid uptake in cultured human fibroblasts

1984 ◽  
Vol 224 (1) ◽  
pp. 309-315 ◽  
Author(s):  
M Feneant ◽  
N Moatti ◽  
J Maccario ◽  
M Gautier ◽  
S Guerroui ◽  
...  
Keyword(s):  
Amino Acid ◽  
Transport System ◽  
Human Fibroblasts ◽  
Diffusion Constant ◽  
Amino Acid Uptake ◽  
Cell Uptake ◽  
Transport Systems ◽  
Acid Uptake ◽  
High Affinity ◽  
Cultured Human Fibroblasts

The influence of cycloleucine on kinetic parameters of uptake of L-alanine, L-proline and L-leucine into cultured human fibroblasts was examined under initial-rate conditions with substrate concentrations of 0.05-10 mM and 5 mM-cycloleucine. Kinetic data obtained by computer analysis showed that, in the absence of cycloleucine, cell uptake was heterogeneous for each amino acid. L-Alanine and L-leucine entered by two transport systems with different affinities; L-proline was taken up by one saturable transport system plus a diffusion-like process. This heterogeneity disappeared in the presence of cycloleucine, since the high-affinity systems were no longer detectable. The remaining process had the same kinetic constants as the low-affinity system for alanine and leucine and a KD similar to the diffusion constant for proline. The influence of cycloleucine on the amino acid uptake was not specific either to the amino acid concerned or to a particular transport system, since the three neutral amino acid-transport systems, A, ASC and L, were involved in these experiments. This influence was shown to be unaffected by the absence of Na+ (for leucine uptake). ATP content of the cells was identical in the presence or in the absence of cycloleucine.

Gamma-Glutamyl-Amino Acids as Signals for the Hormonal Regulation of Amino Acid Uptake by the Mammary Gland of the Lactating Rat

Neonatology ◽  
1985 ◽  
Vol 48 (4) ◽  
pp. 250-256 ◽  
Author(s):  
Juan R. Viña ◽  
Inmaculada R. Puertes ◽  
Juan B. Montoro ◽  
Guillermo T. Saez ◽  
José Viña
Keyword(s):  
Amino Acids ◽  
Mammary Gland ◽  
Amino Acid ◽  
Hormonal Regulation ◽  
Amino Acid Uptake ◽  
Acid Uptake ◽  
Gamma Glutamyl

scholarly journals Pattern and rate of disappearance of gamma-glutamyl transpeptidase activity in fetal and neonatal rat liver.

1983 ◽  
Vol 31 (11) ◽  
pp. 1312-1316 ◽  
Author(s):  
P M Iannaccone ◽  
J Koizumi
Keyword(s):  
Amino Acid ◽  
Bile Duct ◽  
Neonatal Rat ◽  
Acid Transport ◽  
Gamma Glutamyl Transpeptidase ◽  
Gamma Glutamyl ◽  
Duct Epithelium ◽  
Neonatal Liver ◽  
Bile Duct Epithelium ◽  
Glutamyl Transpeptidase

Gamma-glutamyl transpeptidase (gamma-GTP), an amino acid transport enzyme, has been demonstrated in a number of fetal and adult tissues of rodent and man. While the re-expression of the enzyme has been described in epithelia following carcinogen treatment or aging, little is known of the mechanism of its disappearance in some neonatal tissues. A description is presented of the rate and pattern of loss of histologically demonstrable gamma-GTP activity from fetal and neonatal liver of the rat. The number of hepatocytes with histologically demonstrable gamma-GTP activity declines rapidly from the 18th day of gestation. By the 6th day postpartum the activity is demonstrable in clusters of hepatocytes. By the 7th day postpartum there are essentially no hepatocytes with demonstrable activity, although the enzyme remains expressed in bile duct epithelium.

Regulation of cellular glutathione

1989 ◽  
Vol 257 (4) ◽  
pp. L163-L173 ◽  
Author(s):  
S. M. Deneke ◽  
B. L. Fanburg
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Cultured Cells ◽  
Feedback Inhibition ◽  
Reductase Activity ◽  
Transport Systems ◽  
Synthetase Activity ◽  
Gamma Glutamyl Transpeptidase ◽  
Gamma Glutamyl ◽  
Glutamyl Transpeptidase

In addition to its participation in a variety of other biochemical reactions, glutathione (GSH) is a major antioxidant. It is regularly generated intracellularly from its oxidized form by glutathione reductase activity that is coupled with a series of interrelated reactions. Synthesis of GSH also takes place intracellularly by a two-step reaction, the first of which is catalyzed by rate-limiting gamma-glutamylcysteine synthetase activity. Intracellular substrates for GSH are provided both by direct amino acid transport and by a gamma-glutamyl transpeptidase reaction that salvages circulating GSH by coupling the gamma-glutamyl moiety to a suitable amino acid acceptor for transport into the cell. Although the liver is a net synthesizer of circulating GSH, organs such as the kidney salvage GSH through the gamma-glutamyl transpeptidase reaction. Intracellular GSH may be consumed by GSH transferase reactions that conjugate GSH with certain xenobiotics. Elevation of cellular GSH levels in cultured cells in response to hyperoxia or electrophilic agents such as diethylmaleate is coupled with an increase in activity of the Xc- transport system for the amino acids cystine and glutamate. Strategies may be developed for protection against oxidant injury by enhancement of transport systems for precursor amino acids of GSH or by providing substrate that circumvents feedback inhibition of GSH synthesis.

scholarly journals Histochemical localization of gamma glutamyl transpeptidase in the paranodal region of peripheral nerve.

1984 ◽  
Vol 32 (12) ◽  
pp. 1303-1308 ◽  
Author(s):  
B J Mrsulja ◽  
A K Gulati ◽  
A A Zalewski
Keyword(s):  
Amino Acid ◽  
Peripheral Nerve ◽  
Amino Acid Transport ◽  
Myelinated Axon ◽  
Nerve Fibers ◽  
Acid Transport ◽  
Gamma Glutamyl Transpeptidase ◽  
Myelinated Nerve ◽  
Gamma Glutamyl ◽  
Glutamyl Transpeptidase

Gamma glutamyl transpeptidase (GGT), an amino acid transport enzyme, was investigated in normal and degenerated sciatic nerve of rat. The enzyme activity, which is considered to be a marker for cerebrovascular endothelium, was found to be absent in microvessels of normal and degenerated nerves. In the perineurium of normal nerve, GGT activity was faint, while in degenerated nerve, it increased. The most striking finding of this study was the observation of GGT activity at the paranode of each normal myelinated axon. It is interesting that after axotomy (8 weeks), no GGT activity was observed in the Schwann cells of degenerated nerve. Thus, Schwann cell plasmalemma contributed to GGT staining only when this cell was in contact with an axon mature enough to cause it to produce myelin. We conclude that, in peripheral nerve, transmembrane amino acid transport is apparently regional and associated with the paranodal region of myelinated nerve fibers.

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