Figure 2. Pathway for the phosphorylation of cytidine and deoxycytidine.
The biochemical pathway by which cytidine or deoxycytidine may be converted to nucleoside triphosphates and incorporated into RNA or DNA are shown. The figure points out that a deoxycytidine kinase is missing in E. coli and that Drosophila deoxynucleoside kinase (Dm-dNK) can perform this step. Udk- Uridine/ Cytidine kinase, Cmk- CMP kinase, N rd- Ribonucleotide Reductase, Ndk- Nucleotide Diphosphate Kinase.