Two high affinity nucleoside transporters in Leishmania donovani

Bruce Aronow, Kiran Kaur, Kathleen McCartan, Buddy Ullman

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107 Scopus citations


A rapid sampling kinetic technique has been used to evaluate the nucleoside transport functions of Leishmania donovani. The results indicated that L. donovani promastigotes possessed two independent purine nucleoside transporters with nonoverlapping substrate specificity. The first transported inosine, guanosine, and their analogs, while the second carried adenosine, analogs of adenosine, and the pyrimidine nucleosides, uridine, cytidine, and thymidine. The apparent Km values of the two nucleoside permeases for their purine nucleoside substrates were extraordinarily low, in the micromolar range. The organisms were capable of concentrating purine nucleosides from the medium and converting them to the nucleotide level with great efficiency and rapidity. Inosine and adenosine transport could be distinguished by different sensitivities to sulfhydryl reagents, suggesting structural differences between the two transporters. Finally, the two nucleoside transport systems of L. donovani were virtually refractory to inhibition by 4-nitrobenzylthioinosine and dipyridamole, two potent inhibitors of nucleoside entry into mammalian cells.

Original languageEnglish (US)
Pages (from-to)29-37
Number of pages9
JournalMolecular and Biochemical Parasitology
Issue number1
StatePublished - Jan 2 1987


  • Leishmania donovani
  • Nucleoside transport
  • Substrate specificity

ASJC Scopus subject areas

  • Parasitology
  • Molecular Biology


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