Tryptophan transport through transport system T in the human erythrocyte, the Ehrlich cell and the rat intestine

López‐Burillo, Silvia; García‐Sancho, Javier; Herreros, Benito

doi:10.1016/0005-2736(85)90218-4

Cited by 30 publications

(22 citation statements)

References 21 publications

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“…In human erythrocytes, it was shown that system T accepts N-methyl-and N-acetyl-derivatives of tryptophan (11,14). In this study, we have shown that the tryptophan uptake mediated by TAT1 is, in fact, inhibited by N-methyl-and N-acetylderivatives of aromatic amino acids, whereas their methylesters have no effect on TAT1-mediated transport (Fig.…”

Section: Discussionmentioning

confidence: 56%

“…In addition, the transport mediated by TAT1 is an electroneutral facilitated diffusion and not driven by the pH gradient across the plasma membrane, suggesting that TAT1-mediated transport is not coupled with H ϩ -transport. These properties of TAT1 are consistent with those of system T, whereas they are distinct from those of H ϩ /monocarboxylate transporters (10,12,14,(35)(36)(37)(38)(39). It would be interesting to know what structural traits are responsible for the diversity in the substrate selectivity and the ion coupling observed among such structurally related transporters.…”

Section: Discussionmentioning

confidence: 59%

“…Three days after injection the uptake of 14 C-labeled amino acids was measured as described above in the regular uptake solution or Na ϩ -free uptake solution in which NaCl in the regular uptake solution was replaced by choline chloride, containing 0.5-2.0 Ci/ml radiolabeled compounds. For Cl Ϫ -free uptake solution, Cl Ϫ in the Na ϩ uptake solution was replaced by gluconate anion.…”

Section: Expression Of Rat Small Intestine Poly(a)mentioning

confidence: 99%

“…It transports aromatic amino acids in a Na ϩ -independent manner (9 -12). Although it was once proposed that system T is a variant of system L which shows Na ϩ -independent transport of neutral amino acids including aromatic amino acids, system T is distinct in that it accepts Nmethyl amino acids whereas system L does not (11,13,14). Therefore, it is reasonable to assume that transporters subserving system T would belong to a different family with distinct mechanisms of substrate recognition.…”

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confidence: 99%

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Expression Cloning of a Na+-independent Aromatic Amino Acid Transporter with Structural Similarity to H+/Monocarboxylate Transporters

Kim

Kanai

Chairoungdua

et al. 2001

Journal of Biological Chemistry

213

144

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A cDNA was isolated from rat small intestine by expression cloning which encodes a novel Na ؉ -independent transporter for aromatic amino acids. When expressed in Xenopus oocytes, the encoded protein designated as TAT1 (T-type amino acid transporter 1) exhibited Na ؉ -independent and low-affinity transport of aromatic amino acids such as tryptophan, tyrosine, and phenylalanine (K m values: ϳ5 mM), consistent with the properties of classical amino acid transport system T. TAT1 accepted some variations of aromatic side chains because it interacted with amino acid-related compounds such as L-DOPA and 3-O-methyl-DOPA. Because TAT1 accepted N-methyl-and N-acetyl-derivatives of aromatic amino acids but did not accept their methylesters, it is proposed that TAT1 recognizes amino acid substrates as anions. Consistent with this, TAT1 exhibited sequence similarity (ϳ30% identity at the amino acid level) to H ؉ /monocarboxylate transporters. Distinct from H؉ /monocarboxylate transporters, however, TAT1 was not coupled with the H ؉ transport but it mediated an electroneutral facilitated diffusion. TAT1 mRNA was strongly expressed in intestine, placenta, and liver. In rat small intestine TAT1 immunoreactivity was detected in the basolateral membrane of the epithelial cells suggesting its role in the transepithelial transport of aromatic amino acids. The identification of the amino acid transporter with distinct structural and functional characteristics will not only facilitate the expansion of amino acid transporter families but also provide new insights into the mechanisms of substrate recognition of organic solute transporters.

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Section: Discussionmentioning

confidence: 56%

Section: Discussionmentioning

confidence: 59%

Section: Expression Of Rat Small Intestine Poly(a)mentioning

confidence: 99%

mentioning

confidence: 99%

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Expression Cloning of a Na+-independent Aromatic Amino Acid Transporter with Structural Similarity to H+/Monocarboxylate Transporters

Kim

Kanai

Chairoungdua

et al. 2001

Journal of Biological Chemistry

213

144

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“…It was initially assumed that system T was a variant of system L and had a Na + ‐independent transport of neutral amino acids, including aromatic amino acids. However, subsequent studies revealed that in contrast to system L (16–18), system T accepts N‐methyl analogues of the aromatic amino acids. A subclass of system T is TAT 1 (T‐type amino acid transporter) exhibiting Na + ‐independent and low‐affinity transport of tryptophan, tyrosine and phenylalanine, as does system T. In addition, TAT 1 accepts some variations of aromatic side chains because it interacts with amino acid‐related compounds such as L‐dopa and 3‐O‐methyldopa (19).…”

Section: Introductionmentioning

confidence: 99%

New mechanism for amino acid influx into human epidermal Langerhans cells: L‐dopa/proton counter‐transport system

Falck¹,

Bendsöe

Ronquist

2003

Experimental Dermatology

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We have characterized a stereospecific transport mechanism for L-dopa into human epidermal Langerhans cells (LCs). It is different from any other amino acid transport system. It is highly concentrative, largely pH-independent, and independent of exogenous Na þ , glucose and oxygen, and fuelled by a renewable intracellular energy source inhibited by iodoacetate but not by arsenate. We propose that the mechanism is a unidirectional L-dopa/proton counter-transport system. We have recently demonstrated anaerobic glycolysis in human epidermis, which substantiates the need of proton pumps for resident LCs. The findings prompt a re-evaluation of the profound changes LCs undergo when exposed to oxygen in aerobic culture. L-dopa is not metabolized by LCs but can rapidly be dislocated to the intercellular space by certain extracellular amino acids, i.e. LCs can profit by L-dopa in a dualistic way, altogether a remarkable biological phenomenon.

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Aberrant Tyrosine Transport Across the Cell Membrane in Patients With Schizophrenia

Flyckt¹,

Venizelos²,

Edman³

et al. 2001

Arch Gen Psychiatry

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Tryptophan transport through transport system T in the human erythrocyte, the Ehrlich cell and the rat intestine

Cited by 30 publications

References 21 publications

Expression Cloning of a Na+-independent Aromatic Amino Acid Transporter with Structural Similarity to H+/Monocarboxylate Transporters

Expression Cloning of a Na+-independent Aromatic Amino Acid Transporter with Structural Similarity to H+/Monocarboxylate Transporters

New mechanism for amino acid influx into human epidermal Langerhans cells: L‐dopa/proton counter‐transport system

Aberrant Tyrosine Transport Across the Cell Membrane in Patients With Schizophrenia

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