TI  - The splicing factor <prot>U2AF35</prot> mediates critical protein-protein interactions
      in constitutive and enhancer-dependent splicing.
PG  - 1356-68
AB  - The splicing factor U2AF (U2 snRNP auxiliary factor) is a heterodimer with
      subunits of 65 and 35 kD ( <prot>U2AF65</prot>  and  <prot>U2AF35</prot> ). <prot>U2AF65</prot> binds specifically to
      3' splice sites, but previous studies failed to demonstrate a function for
      <prot>U2AF35</prot>. Here, we report that <prot>U2AF35</prot> is required for constitutive splicing
      and also functions as a mediator of enhancer-dependent splicing. Nuclear
      extracts deficient in <prot>U2AF35</prot> were inactive; however, both constitutive and
      enhancer-dependent splicing could be restored by the addition of purified
      recombinant <prot>U2AF35</prot>. In vitro protein-RNA interaction studies with
      pre-mRNAs containing either a constitutive or regulated splicing enhancer
      revealed that  <prot>U2AF35</prot>  directly mediates interactions between  <prot>U2AF65</prot>  and
      proteins bound to the enhancers. Thus,  <prot>U2AF35</prot>  functions as a bridge
      between  <prot>U2AF65</prot>  and the enhancer complex to recruit <prot>U2AF65</prot> to the adjacent
      intron.
AD  - Department of Molecular and Cellular Biology, Harvard University,
