Figure 1.
Metabolism and interconversion of exogenous nucleotides by lymphoid cells. (A) Jurkat and Namalwa cells were incubated for 12 min with 10 μM [γ-32P]ATP and 200 μM UDP, GDP, and AMP, as indicated. The cells were also pretreated with 100 μM Ap5A or 2.5 mM EDTA for 15 min at 37°C before addition of nucleotides. (B) Intact Jurkat cells, Jurkat CD73-transfectants (J-CD73), and their sonicated lysates were incubated for 45 min with 50 μM [3H]AMP in the presence of 500 μM ATP and 30 μM APCP. Aliquots of the mixture were spotted onto PEI-cellullose (A) or SIL-G/UV254 (B) plates, separated by TLC, and developed by autoradiography. Arrows indicate the positions of nucleotide standards, inorganic phosphorus (Pi), adenosine (Ado), inosine (Ino), and hypoxanthine (Hyp). The blanks (Bl) show the radiochemical purity of radiolabeled nucleotides after incubation without lymphoid cells.