Stage-specific development of a novel adenosine transporter in Leishmania donovani amastigotes

Leishmania donovani, like all other kinetoplastida, is a purine auxotroph. Comparative studies of adenosine transport in L. donovani amastigotes and promastigotes revealed that, unlike the promastigote stage, the amastigote possesses two distinct adenosine transporters (T-1 and T-2) both with high affinities (K-m, 1.14 +/- 0.05 and 2.09 +/- 0.13 mu M, respectively). One of these transporters (T-1) appears to be identical with the adenosine/pyrimidine nucleoside transporter of the promastigote reported earlier. The other transporter (T-2) is specific for the amastigote stage and transports only purine nucleosides. The biological significance of this stage-specific de development of the second adenosine transporter has been briefly discussed. (C) 2000 Elsevier Science B.V. All rights reserved.