ribonucleotide reductase B2 subunit (M2 subunit, ribonucleotide reductase small subunit, RRM2, RR2)

Function

• provides precursors for DNA synthesis
• catalyzes the biosynthesis of deoxyribonucleotides from the corresponding ribonucleotides
• heterodimer of a large (M1) & a small chain (M2)
• DNA replication
• 2 distinct regulatory sites have been defined:
  • specificity site, which controls substrate specificity
  • activity site which regulates overall catalytic activity
• substrate-binding catalytic site, located on M1, is formed only in the presence of the second subunit M2

2'-deoxyribonucleoside diphosphate + thioredoxin disulfide + H2O
                      <-->
ribonucleoside diphosphate + thioredoxin

Cofactor: binds 2 Fe+2/Fe+3 per subunit (putative)

Structure

• belongs to the ribonucleoside diphosphate reductase small chain family

Compartment

cytoplasm

Pathology

• ribonucleotide reductase is thought to mediate pathogenesis of the immunodeficiency of
  • adenosine deaminase deficiency
  • purine nucleoside phosphorylase deficiency
• deoxynucleotides that accumulate in lymphoid cells are thought to feed-back inhibit ribonucleotide reductase, preventing DNA replication & cell proliferation

More general terms

• protein subunit
• oligomerizing protein

Component of

• ribonucleotide reductase

Database

• UniProt: http://www.uniprot.org/uniprot/P31350.html
• OMIM: https://mirror.omim.org/entry/180390