title: Ribonucleotide reductase: regulation, regulation, regulation.
abstract: Ribonucleotide reductase (RNR) catalyses the rate limiting step in the production of deoxyribonucleotides needed for DNA synthesis. It is composed of two dissimilar subunits, R1, the large subunit containing the allosteric regulatory sites, and R2, the small subunit containing a binuclear iron center and a tyrosyl free radical. Recent isolation of the mammalian and yeast RNR genes has shown that, in addition to the well documented allosteric regulation, the synthesis of the enzyme is also tightly regulated at the level of transcription. The mRNAs for both subunits are cell-cycle regulated and, in yeast, inducible by DNA damage. Yeast encode a second large subunit gene, RNR3, that is expressed only in the presence of DNA damage. This regulation is thought to provide a metabolic state that facilitates DNA replicational repair processes.
authors.affiliation: Department of Biochemistry, Baylor College of Medicine, Houston, TX 77030.
authors.forename: S J
authors.initials: SJ
authors.lastname: Elledge
authors.forename: Z
authors.initials: Z
authors.lastname: Zhou
authors.forename: J B
authors.initials: JB
authors.lastname: Allen
mesh_terms: D000818:Animals; D001483:Base Sequence; D002453:Cell Cycle / Q000235:genetics; D004249:DNA Damage / Q000235:genetics; D004261:DNA Replication; D015971:Gene Expression Regulation, Enzymologic; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000235:genetics; D012264:Ribonucleotide Reductases / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D014158:Transcription, Genetic
chemical_list: D012333:RNA, Messenger; D012264:Ribonucleotide Reductases