The splicing factor U2AF35 mediates critical protein-protein interactions in constitutive and enhancer-dependent splicing

Genes Dev. 1996 Jun 1;10(11):1356-68. doi: 10.1101/gad.10.11.1356.


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.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Enhancer Elements, Genetic*
  • Nuclear Proteins*
  • Protein Binding
  • RNA Precursors / genetics
  • RNA Splicing*
  • RNA, Messenger / genetics
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Ribonucleoproteins / genetics
  • Ribonucleoproteins / metabolism*
  • Splicing Factor U2AF


  • Nuclear Proteins
  • RNA Precursors
  • RNA, Messenger
  • Recombinant Proteins
  • Ribonucleoproteins
  • Splicing Factor U2AF
  • U2AF1 protein, human