抄録
Equilibrative nucleoside transporters (ENTs) play key roles in many aspects of eukaryote physiology. We isolated and characterized the genes for potential ENTs of rice (designated OsENT1 to 4). By yeast complementation experiments, OsENT2 was shown to be able to uptake adenosine. In competition experiments, the transport of radiolabeled adenosine by OsENT2 was most significantly inhibited by a number of different purine and pyrimidine nucleosides and 2'-deoxynucleosides. This indicates that OsENT2 may possess broad substrate specificity. The OsENT2 promoter drives GUS reporter gene activity in the vasculatures throughout whole plants. Vascular localization of OsENT2 promoter activity prompted us to examine whether this gene products can function as nucleoside cytokinin transporter. Direct measurements demonstrated that OsENT2 was able to mediate uptake of radiolabeled isopentenyl adenosine. Further approaches like RNAi technology are in progress to reveal the physiological roles of OsENT2.
