The Y14 protein communicates to the cytoplasm the position of exon–exon junctions

V.Narry Kim, Jeongsik Yong, Naoyuki Kataoka, Linda Abel, Michael D. Diem, Gideon Dreyfuss

Author Affiliations

  1. V.Narry Kim1,
  2. Jeongsik Yong1,
  3. Naoyuki Kataoka1,
  4. Linda Abel1,
  5. Michael D. Diem1 and
  6. Gideon Dreyfuss*,1
  1. 1 Howard Hughes Medical Institute and Department of Biochemistry & Biophysics, University of Pennsylvania School of Medicine, Philadelphia, PA, 19104‐6148, USA
  1. *Corresponding author. E-mail: gdreyfuss{at}
  1. V.N.Kim and J.Yong contributed equally to this work

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We recently described an RNA‐binding protein, Y14, that binds preferentially to spliced mRNAs and persists in the cytoplasm. Y14 is part of a multi‐protein complex that also contains the mRNA export factor TAP. This suggests that splicing imprints the mRNA with a unique set of proteins that communicate the history of the transcript to the cytoplasm. Here, using microinjection of pre‐mRNAs into Xenopus oocyte nuclei followed by immunoprecipitation of RNase‐fragmented mRNAs from the cytoplasm, we show that Y14 is stably bound to sequences immediately upstream of exon–exon junctions. This feature appears to be unique to Y14. Using monoclonal antibodies that we produced against Aly/REF, another component recently reported to be an mRNA export factor, we show that Aly/REF is associated with spliced mRNAs in the nucleus but is not detectable on mRNAs in the cytoplasm. Thus, we propose that the splicing‐ dependent binding of Y14 provides a position‐specific molecular memory that communicates to the cytoplasm the location of exon and intron boundaries. This novel mechanism may play an important role in post‐splicing events.

  • Received January 2, 2001.
  • Revision received February 22, 2001.
  • Accepted February 23, 2001.
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