Human intestinal es nucleoside transporter: molecular characterization and nucleoside inhibitory profiles.
Cancer Chemother Pharmacol
; 45(4): 273-8, 2000.
Article
em En
| MEDLINE
| ID: mdl-10755314
ABSTRACT
PURPOSE:
To clone and sequence the equilibrative nitrobenzylthioinosine (NBMPR)-sensitive nucleoside transporter (es) from the human small intestine and to examine the capacities of nucleosides and nucleoside analogs to inhibit the uptake of uridine by this transporter.METHODS:
Using PCR, es was cloned from a cDNA library of the human small intestine. The uptake of 3H-uridine (10 microM) by the recombinant es, expressed in Xenopus oocytes, was measured in the presence (2 mM) and absence of nucleosides and nucleoside analogs.RESULTS:
The amino acid sequence of this es transporter was identical to that of the human placental es transporter. Uptake of 3H-uridine by this es transporter was inhibitable by 1 microM NBMPR. Removal of the oxygen from the 3' position or from both the 2' and 3' positions, but not from 2' or 5' position, resulted in a partial or total loss of the capacity of the nucleosides to inhibit 3H-uridine uptake. No modifications of the adenosine base or of the uridine base (except for 3 and 6 positions on uracil) affected nucleoside inhibitory capacity.CONCLUSION:
The es transporters of the human intestine and placenta are identical in their amino acid sequences. Moreover, the inhibitory profiles of various nucleoside analogs in inhibiting the uptake of uridine by the intestinal es transporter are similar to those obtained with the as-yet-uncloned human erythrocyte es transporter. Collectively, these findings suggest that the es transporter does not appear to be functionally variant in the human placenta, small intestine or erythrocytes.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Proteínas de Transporte
/
Intestino Delgado
/
Proteínas de Membrana
/
Nucleosídeos
Limite:
Animals
/
Humans
Idioma:
En
Revista:
Cancer Chemother Pharmacol
Ano de publicação:
2000
Tipo de documento:
Article
País de afiliação:
Estados Unidos