Table 1.

Effects of various NTPs or CCCP on transport activity of Npt1Ct and Npt2Ct a

EffectorRate of a NTP transport (nmol · mg of protein−1 · h−1)b
Npt1Ct, ATPNpt2Ct
ATPGTPUTPCTP
None130.053.475.786.391.1
ATP77.949.461.7
GTP105.03.53.47.3
UTP121.610.968.934.9
CTP130.416.570.639.9
CCCP91.27.110.619.820.9
  • 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.