SR splicing factors serve as adapter proteins for TAP-dependent mRNA export.
The only mammalian RNA binding adapter proteins known to partner with TAP/NXF1, the primary receptor for general mRNA export, are members of the REF family. We demonstrate that at least three shuttling SR (serine/arginine-rich) proteins interact with the same domain of TAP/NXF1 that binds REFs. Included are 9G8 and SRp20, previously shown to promote the export of intronless RNAs. A peptide derived from the N terminus of 9G8 inhibits the binding of both REF and SR proteins to TAP/NXF1 in vitro, and this finding argues for competitive interactions. In Xenopus oocytes, the N terminus of 9G8 exhibits a dominant-negative effect on mRNA export from the nucleus, while addition of excess TAP/NXF1 overcomes this inhibition. Thus, multiple adapters including SR proteins most likely cooperate to recruit multiple copies of TAP/NXF1 for efficient mRNA export.
Huang
Yingqun
Y
Department of Molecular Biophysics and Biochemistry, Howard Hughes Medical Institute, Yale University, New Haven, CT 06536, USA.
Gattoni
Renata
R
Stévenin
James
J
Steitz
Joan A
JA
D000595:Amino Acid Sequence; D000818:Animals; D001120:Arginine / Q000378:metabolism*; D001667:Binding, Competitive; D001692:Biological Transport; D002467:Cell Nucleus / Q000378:metabolism; D005799:Genes, Dominant; D005982:Glutathione Transferase / Q000378:metabolism; D008954:Models, Biological; D008969:Molecular Sequence Data; D029543:Nucleocytoplasmic Transport Proteins / Q000378:metabolism* / Q000502:physiology*; D009865:Oocytes / Q000378:metabolism; D010455:Peptides / Q000737:chemistry; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism* / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012694:Serine / Q000378:metabolism*; D014162:Transfection; D014981:Xenopus
C122111:NXF1 protein, human; D029543:Nucleocytoplasmic Transport Proteins; D010455:Peptides; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D012694:Serine; D001120:Arginine; D005982:Glutathione Transferase