We interpret our results to mean that in mammalian cells ribonucleotide reduction takes place in the cytoplasm and from there the deoxyribonucleotides are transported into the nucleus to serve in DNA synthesis.

Where are ribonucleotides found in the cell?

Ribonucleotides are incorporated in DNA during DNA synthesis and are removed by the ribonucleotide excision repair pathway, which is initiated by RNase H2. Ribonucleotides are markers for the newly synthesized DNA strand and strand-discrimination signals for the mismatch repair system.

What is the function of ribonucleotide reductase?

Ribonucleotide reductase (RNR) is a key enzyme that mediates the synthesis of deoxyribonucleotides, the DNA precursors, for DNA synthesis in every living cell. This enzyme converts ribonucleotides to deoxyribonucleotides, the building blocks for DNA replication, and repair.