TABLE 1.
Effects of various NTPs or CCCP on transport activity of Npt1Ct and Npt2Cta
| Effector | Rate of a NTP transport (nmol · mg of protein−1 · h−1)b
|
||||
|---|---|---|---|---|---|
| Npt1Ct, ATP | Npt2Ct
|
||||
| ATP | GTP | UTP | CTP | ||
| None | 130.0 | 53.4 | 75.7 | 86.3 | 91.1 |
| ATP | 77.9 | 49.4 | 61.7 | ||
| GTP | 105.0 | 3.5 | 3.4 | 7.3 | |
| UTP | 121.6 | 10.9 | 68.9 | 34.9 | |
| CTP | 130.4 | 16.5 | 70.6 | 39.9 | |
| CCCP | 91.2 | 7.1 | 10.6 | 19.8 | 20.9 |
a
Substrate concentrations for labeled nucleotides: for Npt1Ct, 50 μM (ATP); for Npt2Ct, 1,000, 50, 400, and 400 μM (ATP, GTP, UTP, and CTP, respectively). The unlabeled NTPs were used at a 2.5-fold-higher concentration; CCCP was present at 1 mM.
b
Mean of three independent experiments.