The Y14 protein communicates to the cytoplasm the position of exon-exon junctions.
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.
Kim
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VN
Howard Hughes Medical Institute and Department of Biochemistry & Biophysics, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6148, USA.
Yong
J
J
Kataoka
N
N
Abel
L
L
Diem
M D
MD
Dreyfuss
G
G
D021581:Active Transport, Cell Nucleus; D001665:Binding Sites; D002467:Cell Nucleus / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism*; D005091:Exons; D008954:Models, Biological; D012326:RNA Splicing; D016601:RNA-Binding Proteins / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism
C406243:RBM8A protein, human; D016601:RNA-Binding Proteins; D014157:Transcription Factors