Nuclear poly(A)-binding protein PABPN1 is associated with RNA polymerase II during transcription and accompanies the released transcript to the nuclear pore

David G. Bear, Nathalie Fomproix, Teresa Soop, Birgitta Björkroth, Sergej Masich, Bertil Daneholt

Research output: Contribution to journalArticlepeer-review

37 Scopus citations

Abstract

The nuclear poly(A)-binding protein, PABPN1, has been previously shown to regulate mRNA poly(A) tail length and to interact with selected proteins involved in mRNA synthesis and trafficking. To further understand the role of PABPN1 in mRNA metabolism, we used cryo-immunoelectron microscopy to determine the fate of PABPN1 at various stages in the assembly and transport of the Chironomus tentans salivary gland Balbiani ring (BR) mRNA ribonucleoprotein (mRNP) complex. PABPN1 is found on BR mRNPs within the nucleoplasm as well as on mRNPs docked at the nuclear pore. Very little PABPN1 is detected on the cytoplasmic side of the nuclear envelope, suggesting that PABPN1 is displaced from mRNPs during or shortly after passage through the nuclear pore. Surprisingly, we also find PABPN1 associated with RNA polymerase II along the chromatin axis of the BR gene. Our results suggest that PABPN1 binds to the polymerase before, at, or shortly after the start of transcription, and that the assembly of PABPN1 onto the poly(A) tail may be coupled to transcription. Furthermore, PABPN1 remains associated with the released BR mRNP until the mRNP is translocated from the nucleus to the cytoplasm.

Original languageEnglish (US)
Pages (from-to)332-344
Number of pages13
JournalExperimental Cell Research
Volume286
Issue number2
DOIs
StatePublished - Jun 10 2003
Externally publishedYes

Keywords

  • Cryo-immunoelectron microscopy
  • OPMD
  • PABP2
  • PABPN1
  • Polyadenylation
  • Ribonucleoprotein
  • mRNA trafficking

ASJC Scopus subject areas

  • Cell Biology

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