Conversion of UDP to UTP is perform

Conversion of UDP to UTP is performed by NDPK. Substrate specificity of NDPK is low, and the g-phosphate group of ATP (the most abundant nucleotide in cells) is rapidly redistributed to other nucleotides to form various nucleoside triphosphates. Thus the reaction of nucleoside diphosphate kinases can be generalized as follows: NDP + ATP ´ NTP + ADP. The activity of NDPK is very high in most organisms including plants (Hirose and Ashihara, 1984), and the equilibrium constant is almost unity. NDPK activ- ity is not known to be regulated by any allosteric effectors In addition to NDPK’s primary role as a catalyst, many other biological phenomena appear to rely on NDPK activ- ities.