Inhibition of transport system b0,+ in blastocysts by inorganic and organic cations yields insight into the structure of its amino acid receptor site

Winkle, Lon J. Van; Campione, Allan L.; Gorman, James M.

doi:10.1016/0005-2736(90)90100-3

Cited by 37 publications

(14 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, the mutual inhibition alone is insufficient to conclude which specific transport system is involved in PGB transport in the ileum. Phenylalanine enters mammalian cells by as many as six different transport systems, including L, B 0 , B 0,ϩ , y ϩ L, ASC, and T (Shotwell et al, 1981;Van Winkle et al, 1990), with the first four transport systems found in intestine and Caco-2 cells (Nakanishi et al, 1994;Fraga et al, 2002;Pan et al, 2002;Wasa et al, 2004). The early conclusion on system Lmediated PGB transport in the rat ileum was also complicated by lack of mutual inhibition between GBP and PGB in intestine and lack of carrier-mediated uptake of GBP and PGB in Caco-2 cells.…”

Section: Pregabalin (S-mentioning

confidence: 99%

Mediation of Highly Concentrative Uptake of Pregabalin by L-Type Amino Acid Transport in Chinese Hamster Ovary and Caco-2 Cells

Su¹,

Feng

Weber

2005

J Pharmacol Exp Ther

View full text Add to dashboard Cite

Pregabalin (PGB) is a novel drug under development for the treatment of epilepsy, neuropathic pain, fibromyalgia, and generalized anxiety disorder. In this study, we investigated PGB transport in rats, mammalian cell lines, and Xenopus laevis oocytes. In contrast to gabapentin (GBP), PGB absorption in rats showed unique linear pharmacokinetics. PGB entered CHO and Caco-2 cells predominately via Na ϩ -independent processes. Uptake of PGB was mutually exclusive with leucine, GBP and 2-aminobicyclo(2,2,1)heptane-2-carboxylic acid, the substrates preferential for system L. The preloaded PGB in CHO cells was exchangeable with leucine, but at a lower exchange rate than that of leucine and GBP. Dixon plots showed competitive inhibition of leucine uptake by PGB, with a K i value very close to the K m value for PGB uptake (377 versus 363 M).At an extracellular concentration of 300 M, the intracellular PGB concentration in CHO cells reached 1.5-and 23-fold higher than that of GBP and leucine, respectively. In contrast, at clinically relevant concentrations, PGB seemed not to interact with GABA transport in GAT1, GAT2, and GAT3 cell lines, system y ϩ , b 0,ϩ , B 0,ϩ , and B 0 transport activities in Caco-2 and NBL-1 cells, and the b 0,ϩ -like transport activity in rBAT cRNAinjected X. laevis oocytes. Taken together, these results suggest that L-type transport is the major transport route for PGB and GBP uptake in mammalian cells. The differential affinity of PGB and GBP at L-type system leads to more concentrative accumulation of PGB than GBP, which may facilitate PGB transmembrane absorption in vivo.

show abstract

Section: Pregabalin (S-mentioning

confidence: 99%

Mediation of Highly Concentrative Uptake of Pregabalin by L-Type Amino Acid Transport in Chinese Hamster Ovary and Caco-2 Cells

Su¹,

Feng

Weber

2005

J Pharmacol Exp Ther

View full text Add to dashboard Cite

show abstract

“…These include the cationic amino acid transporter (system y ϩ ) in human erythrocytes (1), the broad-scope amino acid transporter (b 0,ϩ ), and the choline transporter in mouse blastocysts (2,3). This hypothesis was postulated to explain the increase in the rate of entry that occurs when the standard NaCl medium is replaced by isotonic sucrose and the reduction in the apparent K m for the cationic substrate that results from the same substitution.…”

mentioning

confidence: 99%

“…It has been suggested that they might represent a family of closely related proteins with a common evolutionary origin. The family would include system y ϩ , system b 0,ϩ , the choline transporter, and the neutral amino acid transport systems ASC and asc; the last two are Na-dependent and Na-independent transport systems for alanine, serine, and cysteine, respectively (1)(2)(3)6).…”

mentioning

confidence: 99%

See 1 more Smart Citation

Changes in Membrane and Surface Potential Explain the Opposite Effects of Low Ionic Strength on the Two Lysine Transporters of Human Erythrocytes

Devés

Angelo

1996

Journal of Biological Chemistry

View full text Add to dashboard Cite

The sucrose-induced stimulation of lysine influx in human erythrocytes has been attributed to the removal of a competitive inhibition exerted by Na ؉ on system y . NaCl replacement with sucrose increased influx through system y ؉ L, but decreased influx through system y ؉ . We conclude that 1) the inhibition of system y ؉ is a response to the membrane depolarization that results from chloride removal, and 2) the stimulation of system y ؉ L is due to the enhancement of the negative surface potential. Consistently, lysine influx through system y ؉ L (in sucrose medium) was reduced by Na Several transport systems for cationic permeants have been proposed to contain an Na ϩ binding region within the substrate site. These include the cationic amino acid transporter (system y ϩ ) in human erythrocytes (1), the broad-scope amino acid transporter (b 0,ϩ ), and the choline transporter in mouse blastocysts (2, 3). This hypothesis was postulated to explain the increase in the rate of entry that occurs when the standard NaCl medium is replaced by isotonic sucrose and the reduction in the apparent K m for the cationic substrate that results from the same substitution. In erythrocytes, lysine uptake (5 M, 20°C) was found to be 3-fold higher in isotonic sucrose medium than in 150 mM NaCl, while the apparent K m changed from 59 M in NaCl to 15 M in sucrose (1). Similarly, in blastocysts, Na ϩ replacement by uncharged osmolites induced an approximately 3-fold increase in lysine influx (0.42 M, 37°C), which was accompanied by a shift in apparent K m from 61 to 5 M (2).The hypothesis stating that an Na ϩ binding site exists within the substrate site of cationic amino acid transporters has given rise to some considerations of general significance. It has been remarked that it is consistent with the proposal that the Na ϩ

show abstract

“…One (y + ), is specific for cationic amino acids [1] ; the others (B o,+ , b o,+ and y + L) also transport zwitterionic amino acids [2][3][4][5][6][7]. B o,+ is Na + -dependent and y + and b o,+ are Na + -independent.…”

Section: Introductionmentioning

confidence: 99%

Cloning and functional expression of a cDNA from rat jejunal epithelium encoding a protein (4F2hc) with system y+L amino acid transport activity

Yao

Muzyka

Elliott

et al. 1998

Biochemical Journal

View full text Add to dashboard Cite

Two different protein families, designated CAT (cationic amino acid transporter) and BAT (broad-specificity amino acid transporter) mediate the plasma membrane transport of cationic amino acids in animal cells. CAT transporters have 12-14 transmembrane domains and are selective for cationic amino acids. BAT proteins, in contrast, have one to four transmembrane domains and induce the transport of both cationic and zwitterionic amino acids when expressed in Xenopus oocytes. Mutations in the human BAT gene cause type I cystinuria, a disease affecting the ability of intestinal and renal brush border membranes to transport cationic amino acids and cystine. We have used functional expression cloning in oocytes to isolate a BAT-related cDNA from rat jejunal epithelium. The cDNA encodes the rat 4F2 heavy chain (4F2hc) cell-surface antigen, a 527-residue (60 kDa) protein that is 26% identical in amino acid sequence with rat renal BAT (also known as NBAT/D2). Expression of rat jejunal 4F2hc in oocytes induced the lysine-inhibitable Na+-dependent influx of leucine and the leucine-inhibitable Na+-independent influx of lysine. Lysine efflux was stimulated by extracellular (Na+ plus leucine). These characteristics identify the expressed amino acid transport activity as system y+L, a transporter that has been implicated in basal membrane transport of cationic amino acids in intestine, kidney and placenta.

show abstract

Inhibition of transport system b0,+ in blastocysts by inorganic and organic cations yields insight into the structure of its amino acid receptor site

Cited by 37 publications

References 21 publications

Mediation of Highly Concentrative Uptake of Pregabalin by L-Type Amino Acid Transport in Chinese Hamster Ovary and Caco-2 Cells

Mediation of Highly Concentrative Uptake of Pregabalin by L-Type Amino Acid Transport in Chinese Hamster Ovary and Caco-2 Cells

Changes in Membrane and Surface Potential Explain the Opposite Effects of Low Ionic Strength on the Two Lysine Transporters of Human Erythrocytes

Cloning and functional expression of a cDNA from rat jejunal epithelium encoding a protein (4F2hc) with system y+L amino acid transport activity

Contact Info

Product

Resources

About