Actin bound to the heterogeneous nuclear ribonucleoprotein hrp36 is associated with Balbiani ring mRNA from the gene to polysomes

Piergiorgio Percipalle, Jian Zhao, Brian Pope, Alan Weeds, Uno Lindberg, Bertil Daneholt

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Abstract

In the salivary glands of the dipteran Chironomus tentans, a specific messenger ribonucleoprotein (mRNP) particle, the Balbiani ring (BR) granule, can be visualized during its assembly on the gene and during its nucleocytoplasmic transport. We now show with immunoelectron microscopy that actin becomes associated with the BR particle concomitantly with transcription and is present in the particle in the nucleoplasm. DNase I affinity chromatography experiments with extracts from tissue culture cells indicate that both nuclear and cytoplasmic actin are bound to the heterogeneous RNP (hnRNP) protein hrp36, but not to the hnRNP proteins hrp23 and hrp45. The interaction is likely to be direct as purified actin binds to recombinant hrp36 in vitro. Furthermore, it is demonstrated by cross linking that nuclear as well as cytoplasmic actin are bound to hrp36 in vivo. It is known that hrp36 is added cotranscriptionally along the BR mRNA molecule and accompanies the RNA through the nuclear pores and into polysomes. We conclude that actin is likely to be bound to the BR transcript via hrp36 during the transfer of the mRNA from the gene all the way into polysomes.

Original languageEnglish (US)
Pages (from-to)229-235
Number of pages7
JournalJournal of Cell Biology
Volume153
Issue number1
DOIs
StatePublished - Apr 2 2001

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Keywords

  • Actin
  • Balbiani rings
  • Heterogeneous nuclear ribonucleoprotein
  • Nucleocytoplasmic transport
  • Premessenger ribonucleoprotein particles

ASJC Scopus subject areas

  • Cell Biology

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