The splicing factor U2AF35 mediates critical protein-protein interactions in constitutive and enhancer-dependent splicing.
The splicing factor U2AF (U2 snRNP auxiliary factor) is a heterodimer with subunits of 65 and 35 kD (U2AF65 and U2AF35). U2AF65 binds specifically to 3' splice sites, but previous studies failed to demonstrate a function for U2AF35. Here, we report that U2AF35 is required for constitutive splicing and also functions as a mediator of enhancer-dependent splicing. Nuclear extracts deficient in U2AF35 were inactive; however, both constitutive and enhancer-dependent splicing could be restored by the addition of purified recombinant U2AF35. In vitro protein-RNA interaction studies with pre-mRNAs containing either a constitutive or regulated splicing enhancer revealed that U2AF35 directly mediates interactions between U2AF65 and proteins bound to the enhancers. Thus, U2AF35 functions as a bridge between U2AF65 and the enhancer complex to recruit U2AF65 to the adjacent intron.
Zuo
P
P
Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
Maniatis
T
T
D004742:Enhancer Elements, Genetic; D009687:Nuclear Proteins; D011485:Protein Binding; D012322:RNA Precursors / Q000235:genetics; D012326:RNA Splicing; D012333:RNA, Messenger / Q000235:genetics; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012261:Ribonucleoproteins / Q000235:genetics / Q000378:metabolism*; D000072668:Splicing Factor U2AF
D009687:Nuclear Proteins; D012322:RNA Precursors; D012333:RNA, Messenger; D011994:Recombinant Proteins; D012261:Ribonucleoproteins; D000072668:Splicing Factor U2AF; C076753:U2AF1 protein, human