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 A rapid method for the functional reconstitution of amino acid transport systems from rat liver plasma membranes. Partial purification of System A

1988 ◽  
Vol 255 (3) ◽  
pp. 963-969 ◽  
Author(s):  
A R Quesada ◽  
J D McGivan
Keyword(s):  
Amino Acid ◽  
Rapid Method ◽  
Amino Acid Transport ◽  
Plasma Membranes ◽  
Transport Systems ◽  
Partial Purification ◽  
Acid Transport ◽  
Transport Activity ◽  
System A ◽  
System L

A rapid method for the functional reconstruction of amino acid transport from liver plasma-membrane vesicles using the neutral detergent decanoyl-N-glucamide (‘MEGA-10’) is described. The method is a modification of that previously employed in this laboratory for reconstitution of amino acid transport systems from kidney brush-border membranes [Lynch & McGivan (1987) Biochem. J. 244, 503-508]. The transport activities termed ‘System A’, ‘System N’, and ‘System L’ are all reconstituted. The reconstitution procedure is rapid and efficient and is suitable as an assay for transport activity in studies involving membrane fractionation. By using this reconstitution procedure, System A transport activity was partially purified by lectin-affinity chromatography.

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

Inhibition of system a amino acid transport activity by ethanol in bewo choriocarcinoma cells

2002 ◽  
Vol 187 (1) ◽  
pp. 209-216 ◽  
Author(s):  
Chandra R. Jones ◽  
Sonne R. Srinivas ◽  
Lawrence D. Devoe ◽  
Vadivel Ganapathy ◽  
Puttur D. Prasad
Keyword(s):  
Amino Acid ◽  
Amino Acid Transport ◽  
Acid Transport ◽  
Transport Activity ◽  
System A ◽  
Choriocarcinoma Cells

scholarly journals Leptin Affects System A Amino Acid Transport Activity in the Human Placenta: Evidence for STAT3 Dependent Mechanisms

Placenta ◽  
2009 ◽  
Vol 30 (4) ◽  
pp. 361-367 ◽  
Author(s):  
F. von Versen-Höynck ◽  
A. Rajakumar ◽  
M.S. Parrott ◽  
R.W. Powers
Keyword(s):  
Amino Acid ◽  
Human Placenta ◽  
Amino Acid Transport ◽  
Acid Transport ◽  
Transport Activity ◽  
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

scholarly journals Interactions between the thiol-group reagent N-ethylmaleimide and neutral and basic amino acid transporter-related amino acid transport

1999 ◽  
Vol 343 (1) ◽  
pp. 169-176 ◽  
Author(s):  
George J. PETER ◽  
Anthony DAVIES ◽  
Peter W. WATT ◽  
Jacqueline BIRRELL ◽  
Peter M. TAYLOR
Keyword(s):  
Amino Acid ◽  
Amino Acid Transport ◽  
Basic Amino Acid ◽  
Thiol Group ◽  
Neutral Amino Acid ◽  
Acid Transport ◽  
Transport Activity ◽  
Direct Role ◽  
Cationic Amino Acid

The neutral and basic amino acid transport protein (NBAT) expressed in renal and jejunal brush-border membranes is involved in amino acid and cystine absorption. NBAT mutations result in Type 1 cystinuria. A C-terminal myc-tagged NBAT (NBATmyc) retains the amino acid transport and protein-protein interaction properties of NBAT when expressed in Xenopusoocytes. Neutral amino acid (Ala, Phe)-cationic amino acid (Arg) heteroexchanges related to NBATmyc expression in oocytes are inactivated by treatment with the thiol-group reagent N-ethylmaleimide (NEM), although significant Arg-Arg and Ala-Ala homoexchanges persist. Inactivation of heteroexchange activity by NEM is accompanied by loss of > 85% of alanine and cystine uptake, with smaller (< 50%) inhibition of arginine and phenylalanine uptake. NEM-sensitive cystine uptake and arginine-alanine heteroexchange (system b0,+ activity) are not expressed by an NBAT truncation mutant (NBATmyc-Sph1) lacking the 13 C-terminal amino acid residues, but the mutant expresses NEM-resistant transport activity (system y+L-like) equivalent to that of full-length NBATmyc. The deleted region of NBATmyc-Sph1 contains two cysteine residues (671/683) which may be the targets of NEM action. The synthetic amino acid 2-trifluoromethylhistidine (TFMH) stimulated alanine efflux at pH 7.5 and arginine at pH 5.5, but not vice versa, establishing the existence of distinct pathways for cationic and neutral amino acid homoexchange (TFMH is zwitterionic at pH 7.5 and cationic at pH 5.5). We suggest that NBAT expresses a combination of system b0,+ and y+L-like activities, possibly by interacting with different light-chain subunits endogenous to oocytes (as does the homologous 4F2hc protein). The C-terminus of NBAT may also have an additional, direct role in the mechanism of System b0,+ transport (the major transport activity that is defective in Type 1 cystinuria).

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