On the regulation of deoxyribonucleotide synthesis.

The results reviewed here demonstrate the feasibility of measuring the turnover of pyrimidine dNTPs in cultured cells and of relating such data to rates of DNA synthesis. Growing 3T6 cells appear to contain two kinetically distinct pools of dCTP. One pool is preferentially labeled by reduction of CDP and used for DNA synthesis, the second pool is preferentially labeled by phosphorylation of deoxycytidine. Within the time resolution of our experiments dTTP does not show similar compartmentation. We have also found that pyrimidine dNTPs continue to be synthesized, albeit at reduced rate, when DNA replication is blocked.