title: Inhibition of uridine-cytidine kinase by 5-azacytidine 5'-triphosphate.
abstract: 5-Azacytidine 5'-triphosphate (5-aza-CTP) inhibited the phosphorylation of uridine, cytidine, and 5-azacytidine (5-aza-C) in a reaction catalyzed by uridine-cytidine kinase. The inhibition appeared to be competitive with respect to the adenosine 5'-triphosphate and noncompetitive with respect to nucleoside substrates. 5-aza-CTP was a potent inhibitor of 5-aza-C phosphorylation but a weak inhibitor of uridine and cytidine phosphorylation. These results suggest that the feedback inhibition of uridine-cytidine kinase by 5-aza-CTP may limit the amount of intracellular nucleotide analog formed in drug-treated cells.
mesh_terms: D001374:Azacitidine / Q000494:pharmacology*; D003562:Cytidine; D003597:Cytosine Nucleotides / Q000494:pharmacology*; D003864:Depression, Chemical; D005246:Feedback; D007700:Kinetics; D009711:Nucleotides / Q000096:biosynthesis; D010770:Phosphotransferases / Q000037:antagonists & inhibitors*; D014541:Uridine Kinase / Q000037:antagonists & inhibitors*
chemical_list: D003597:Cytosine Nucleotides; D009711:Nucleotides; D003562:Cytidine; D010770:Phosphotransferases; D014541:Uridine Kinase; D001374:Azacitidine