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ENZYME entry: EC

Accepted Name
bacteriophage T4 restriction endoribonuclease RegB
Reaction catalysed
a [pre-mRNA]-containing guanosine-adenosine + H2O <=> a 5' hydroxy-guanosine-[pre-mRNA fragment] + a [pre-mRNA fragment]-3'-adenosine-3'-phosphate
  • The enzyme from bacteriophage T4 cleaves early mRNAs between Ap and Gp at one specific specific GpGpApGp site, favoring their further transition to middle-phase mRNA.
  • The activity is enhanced by Ribosomal S1 protein.
  • The enzyme catalyzes a two-stage endonucleolytic cleavage.
  • The first reaction produces 5'-hydroxy-phosphooligonucletides and 3'-phosphooligonucleotides ending with 2',3'-cyclic phosphodiester, which are released from the enzyme.
  • The enzyme then hydrolyzes these cyclic compounds in a second reaction that takes place only when all the susceptible 3',5'-phosphodiester bonds have been cyclised.
  • The second reaction is a reversal of the first reaction using the hydroxyl group of water instead of the 5'-hydroxyl group of ribose.
  • The overall process is that of a phosphorus-oxygen lyase followed by hydrolysis to form the 3'-nucleotides.
PRIAM enzyme-specific profiles4.6.1.25
KEGG Ligand Database for Enzyme Nomenclature4.6.1.25
IUBMB Enzyme Nomenclature4.6.1.25
MEDLINEFind literature relating to
Rhea expert-curated reactions4.6.1.25

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