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A 3' exonuclease that specifically interacts with the 3' end of histone mRNA.

Metazoan histone mRNAs end in a highly conserved stem-loop structure followed by ACCCA. Previous studies have suggested that the stem-loop binding protein (SLBP) is the only protein binding this region. Using RNA affinity purification, we identified a second protein, designated 3'hExo, that contains a SAP and a 3' exonuclease domain and binds the same sequence. Strikingly, 3'hExo can bind the stem-loop region both separately and simultaneously with SLBP. Binding of 3'hExo requires the terminal ACCCA, whereas binding of SLBP requires the 5' side of the stem-loop region. Recombinant 3'hExo degrades RNA substrates in a 3'-5' direction and has the highest activity toward the wild-type histone mRNA. Binding of SLBP to the stem-loop at the 3' end of RNA prevents its degradation by 3'hExo. These features make 3'hExo a primary candidate for the exonuclease that initiates rapid decay of histone mRNA upon completion and/or inhibition of DNA replication.

Pubmed ID: 14536070


  • Dominski Z
  • Yang XC
  • Kaygun H
  • Dadlez M
  • Marzluff WF


Molecular cell

Publication Data

August 10, 2003

Associated Grants

  • Agency: NIGMS NIH HHS, Id: GM29832

Mesh Terms

  • Amino Acid Sequence
  • Animals
  • Baculoviridae
  • Cloning, Molecular
  • DNA
  • Exonucleases
  • HeLa Cells
  • Histones
  • Humans
  • Mass Spectrometry
  • Models, Genetic
  • Molecular Sequence Data
  • Nuclear Proteins
  • Precipitin Tests
  • Protein Binding
  • Protein Structure, Tertiary
  • RNA
  • RNA, Messenger
  • RNA-Binding Proteins
  • Rabbits
  • Time Factors
  • Two-Hybrid System Techniques
  • mRNA Cleavage and Polyadenylation Factors