Table 1

Competitive inhibition by various substrates of [α-35S]dATP uptake into proteoliposomes containing the DNC

Substrate Ki, μM
ATP470  ± 50
ADP32  ± 3.4
GDP197  ± 22
CDP284  ± 27
UDP380  ± 40
dADP14  ± 1.2
dGDP55  ± 5.9
dCDP99  ± 9.8
dTDP117  ± 13
dUDP179  ± 19
dGTP230  ± 25
dCTP423  ± 39
dTTP595  ± 62
dUTP963  ± 94
ddATP25  ± 2.3
ddGTP60  ± 5.3
ddCTP70  ± 7.4
ddTTP68  ± 7.1
  • The concentration of [α-35S]dATP was 20–1,000 μM. Competing substrates were added at appropriate concentrations. For other conditions, see Fig. 3b. The Ki values were calculated from double-reciprocal plots of the rate of [α-35S]dATP uptake versus substrate concentration. The values are averages ± SD from at least three experiments.