Protein Domain : Ribonucleotide reductase R1 subunit, N-terminal IPR008926

Type	Homologous_superfamily
Description	The large subunit (R1) of ribonucleotide reductase (RNR), is an essential enzyme required for DNA replication and DNA repair. In both Escherichia coli and higher organisms, the enzyme consists of two non-identical subunits, a dimer of an 85kDa protein, R1, and a dimer of a 45kDa protein, R2. Both subunits are essential for RNR enzyme activity - R1 contains, in the substrate binding site, the reducing active cysteine pair and R2 provides a catalytically essential organic radical. R1 is able to bind and reduce the four common ribonucleoside diphosphates. Substrate specificity is determined by nucleoside triphosphates binding to a protein site different from the active site and acting as allosteric effectors. Thus the presence of ATP makes the enzyme reduce CDP and UDP, dGTP favours ADP reduction and dTTP favours GDP reduction. dATP is a general inhibitor. This provides a mechanism for a balanced enzymatic production of building blocks for DNA synthesis [ ]. This superfamily represents a mainly alpha domain found at the N terminus of the ribonucleotide reductase R1 subunit [ ].
Short Name	RNR_R1-su_N