Ribonuclease H2-B is a subunit of the eukaryotic RNase H complex which cleaves RNA-DNA hybrids
Ribonuclease H2B is one of the three proteins of eukaryotic RNase H2 complex that is required for nucleic acid binding and hydrolysis. RNase H is classified into two families, type I (prokaryotic RNase HI, eukaryotic RNase H1 and viral RNase H) and type II (prokaryotic RNase HII and HIII, and eukaryotic RNase H2/HII). RNase H endonucleolytically hydrolyzes an RNA strand when it is annealed to a complementary DNA strand in the presence of divalent cations, in DNA replication and repair. The enzyme can be found in bacteria, archaea, and eukaryotes. Most prokaryotic and eukaryotic genomes contain multiple RNase H genes. Despite a lack of evidence for homology from sequence comparisons, type I and type II RNase H share a common fold and similar steric configurations of the four acidic active-site residues, suggesting identical or very similar catalytic mechanisms. Eukaryotic RNase HII is active during replication and is believed to play a role in removal of Okazaki fragment primers and single ribonucleotides in DNA-DNA duplexes. Eukaryotic RNase HII is functional when it forms a complex with RNase H2B and RNase H2C proteins. It is speculated that the two accessory subunits are required for correct folding of the catalytic subunit of RNase HII. Mutations in the three subunits of human RNase HII cause neurological disorder.
Comment:Mammalian RNase H2/II is a heterotrimeric complex of the RNase H2A, H2B, and H2C proteins that are required for RNase H2/II activity and function.
Structure:3KIO_B, Mouse RNase H2/II heterotrimeric interface at 4.0 A
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