Table 1. Analysis of the Competing Effects of Potential Substrates on PAPST2-Mediated Import.
| Effector | Import of [α32P]-ATP (%) | SE (±) |
|---|---|---|
| None | 100 | - |
| ATP | 9.4 | 1.1 |
| ADP | 22.8 | 1.8 |
| PAP | 17.9 | 3.5 |
| PAPS | 38.4 | 7.4 |
| dATP | 17.8 | 3.3 |
| AMP | 73.9 | 11.6 |
| Adenine | 76.2 | 9.6 |
| Adenosine | 85.6 | 12.9 |
| ADP-Glc | 84.9 | 7.4 |
| 2,3 cyclo-AMP | 86.4 | 9.9 |
| 3,5 cyclo-AMP | 95.4 | 12.3 |
| GTP | 79.9 | 10.6 |
| GDP | 96.3 | 12.5 |
| GMP | 82.6 | 12.4 |
| dGTP | 75.2 | 5.4 |
| CoA | 56.1 | 7.1 |
| FAD | 72.6 | 10.6 |
| NAD | 88.6 | 14.9 |
| NADP | 85.4 | 12.4 |
| APS | 87.4 | 12.9 |
Uptake of [α32P]-ATP by PAPST2 into liposomes loaded with 20 mM ATP was measured at a substrate concentration of 50 µM. Unlabeled effectors were applied in 10-fold excess, and transport was allowed for 10 min. Rates of nucleotide uptake represent net values (minus control: liposomes containing solely buffer) and are given as percentage compared with nonaffected transport (none; set to 100%). Data are the mean of at least three independent experiments; standard errors (SE) are given.