Ribonucleotide reductase subunits
ribonucleotide reductase subunits
The importance of ribonucleotide reductase (RNR) lies in its unique ability to catalyze the rate-limiting step of the reduction of ribonucleotides (NDPs) to the corresponding deoxyribonucleotides (dNDPs), the precursors of DNA. Mammalian RNRs consist of two homodimeric subunits, which associate to form the holoenzyme. The large RRM1 dimer contains the catalytic site, whereas the smaller dimer (RRM2 or RRM2B) contains an oxygen-requiring di-iron tyrosyl-radical site, which is essential for catalysis.