scholarly journals Evidence for a regulatory protein involved in the increased activity of system A for neutral amino acid transport in osmotically stressed mammalian cells.

1994 ◽  
Vol 91 (20) ◽  
pp. 9569-9573 ◽  
Author(s):  
B. Ruiz-Montasell ◽  
M. Gomez-Angelats ◽  
F. J. Casado ◽  
A. Felipe ◽  
J. D. McGivan ◽  
...  
Keyword(s):  
Amino Acid ◽  
Amino Acid Transport ◽  
Mammalian Cells ◽  
Regulatory Protein ◽  
Neutral Amino Acid ◽  
Acid Transport ◽  
System A ◽  
Increased Activity

scholarly journals Electrogenic Na+-dependentl-alanine transport in the lizard duodenum. Involvement of systems A and ASC

2001 ◽  
Vol 280 (3) ◽  
pp. R612-R622
Author(s):  
Virtudes Medina ◽  
Antonio Lorenzo ◽  
Mario Dı́az
Keyword(s):  
Amino Acid ◽  
Amino Acid Transport ◽  
Short Circuit ◽  
Duodenal Mucosa ◽  
Neutral Amino Acid ◽  
Acid Transport ◽  
Transport Activity ◽  
System A ◽  
Alanine Transport ◽  
Gallotia Galloti

l-Alanine transport across the isolated duodenal mucosa of the lizard Gallotia galloti has been studied in Ussing chambers under short-circuit conditions. Net l-alanine fluxes, transepithelial potential difference (PD), and short-circuit current ( Isc) showed concentration-dependent relationships. Na+-dependent l-alanine transport was substantially inhibited by the analog α-methyl aminoisobutyric acid (MeAIB). Likewise, MeAIB fluxes were completely inhibited byl-alanine, indicating the presence of system A for neutral amino acid transport. System A transport activity was electrogenic and exhibited hyperbolic relationships for net MeAIB fluxes, PD, and Isc, which displayed similar apparent K m values. Na+-dependentl-alanine transport, but not MeAIB transport, was partially inhibited by l-serine and l-cysteine, indicating the participation of system ASC. This transport activity represents the major pathway for l-alanine absorption and seemed to operate in an electroneutral mode with a negligible contribution to the l-alanine-induced electrogenicity. It is concluded from the present study that the active Na+-dependent l-alanine transport across the isolated duodenal mucosa of Gallotia galloti results from the independent activity of systems A and ASC for neutral amino acid transport.

scholarly journals The role of system A for neutral amino acid transport in the regulation of cell volume

2001 ◽  
Vol 18 (1) ◽  
pp. 27-38 ◽  
Author(s):  
Ovidio Bussolati ◽  
Valeria Dall'Asta ◽  
Renata Franchi-Gazzola ◽  
Roberto Sala ◽  
Bianca Maria Rotoli ◽  
...  
Keyword(s):  
Amino Acid ◽  
Cell Volume ◽  
Amino Acid Transport ◽  
Neutral Amino Acid ◽  
Acid Transport ◽  
System A

The stimulation of Na,K,Cl cotransport and of system A for neutral amino acid transport is a mechanism for cell volume increase during the cell cycle

1996 ◽  
Vol 10 (8) ◽  
pp. 920-926 ◽  
Author(s):  
Ovidio Bussolati ◽  
Jacopo Uggeri ◽  
Silvana Belletti ◽  
Valeria Dall'Asta ◽  
Gian C. Gazzola
Keyword(s):  
Cell Cycle ◽  
Amino Acid ◽  
Cell Volume ◽  
Amino Acid Transport ◽  
Neutral Amino Acid ◽  
Acid Transport ◽  
Volume Increase ◽  
System A ◽  
Stimulation Of

Neutral amino acid transport by isolated small intestinal cells from guinea pigs

1991 ◽  
Vol 261 (6) ◽  
pp. G1030-G1036 ◽  
Author(s):  
J. R. Del Castillo ◽  
R. Muniz
Keyword(s):  
Amino Acid ◽  
Amino Acid Transport ◽  
Incubation Medium ◽  
Isobutyric Acid ◽  
Neutral Amino Acid ◽  
Acid Transport ◽  
Independent System ◽  
Isolated Enterocytes ◽  
System A ◽  
System L

Neutral amino acid transport was examined by using isolated enterocytes. Cells transport L-alanine by at least three different mechanisms: two Na(+)-dependent systems (A and ASC) and one Na(+)-independent mechanism (system L), in addition to passive entry. System A was characterized acterized by measuring the Na(+)-dependent alpha-(methylamino)isobutyric acid (MeAIB) uptake. Na(+)-dependent MeAIB uptake was concentrative and saturable. Vmax was obtained at 80mM Na+ in the incubation medium and Kt app for Na+ was 21.5 mM. Kt app for MeAIB was 6.75 +/- 0.37 mM and the Vmax was 14.2 +/- 0.3 nmol.mg-1.min-1. System ASC was studied by evaluating the Na(+)-dependent L-alanine uptake, insensitive to MeAIB and inhibitable by L-serine and L-cysteine. Uptake by this mechanism was also concentrative and saturable. Maximal uptake was obtained with 80 mM Na+ in the incubation medium and Kt app for Na+ was 29.7 mM. Kt app for L-alanine was 7.02 +/- 0.61 mM and Vmax was 5.44 +/- 0.19 nmol.mg-1.min-1. The Na(+)-independent system L was studied by measuring cycloleucine uptake in Na(+)-free medium. It had a saturable and a nonsaturable component. Only the saturable component was concentrative; it was inhibited by 2-amino-2-norbornanecarboxylic acid and was capable of mediating exchange diffusion. Kt app for cycloleucine was 4.05 +/- 0.72 mM and the Vmax was 31.9 +/- 1.3 nmol.mg-1.min-1. These results confirm the existence of Na(+)-dependent systems A and ASC and Na(+)-independent system L in isolated enterocytes.

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