TI  - Cloning and characterization of <prot>hTAFII18</prot>, <prot>hTAFII20</prot> and <prot>hTAFII28</prot>: three
      subunits of the human transcription factor <prot>TFIID</prot>.
PG  - 1520-31
AB  - We have cloned cDNAs encoding three novel TAFIIs [<prot>TATA-binding protein</prot>
      (<prot>TBP</prot>)-associated factors] from the human (h) HeLa cell <prot>TFIID</prot> complexes
       <prot>hTAFII28</prot> ,  <prot>hTAFII20</prot>  and  <prot>hTAFII18</prot> . <prot>hTAFII28</prot> is a core <prot>hTAFII</prot> present in both
      of the previously described <prot>hTFIID</prot> species which either lack or contain
      <prot>hTAFII30</prot> (<prot><prot>hTFIID</prot> alpha</prot> and <prot><prot>hTFIID</prot> beta</prot> respectively), and is the homologue
      of Drosophila (d)<prot>TAFII30 beta</prot>. <prot>hTAFII18</prot> is a novel <prot>hTAFII</prot> which shows
      homology to the N-terminal region of the yeast <prot>TAFIISPT3</prot>, but has no known
      Drosophila counterpart. In contrast to <prot>hTAFII28</prot>, <prot>hTAFII18</prot> is a <prot><prot>TFIID</prot>
      beta</prot>-specific <prot>hTAFII</prot>. <prot>hTAFII20</prot> is the homologue of <prot>p22</prot>, an alternatively
      spliced form of d<prot>TAFII30 alpha</prot> (<prot>p32</prot>). Using a combination of protein
      affinity chromatography and cotransfection and immunoprecipitation assays,
      we have identified a series of in vitro and intracellular interactions
      among the novel hTAFIIs and between the novel hTAFIIs and <prot>hTAFII30</prot> or TBP.
      We show that  <prot>hTAFII28</prot>  interacts with  <prot>hTAFII18</prot>  both in vitro and
      intracellularly; in contrast to its Drosophila homologue,  <prot>hTAFII28</prot>  also
      interacts directly with  <prot>TBP</prot> . Deletion analysis indicates that  <prot>TBP</prot>  and
       <prot>hTAFII18</prot>  bind to distinct domains of   <prot>hTAFII28</prot>  .    <prot>hTAFII18</prot>    also interacts
      with  <prot>TBP</prot> , but it interacts more strongly with  <prot>hTAFII28</prot>  and  <prot>hTAFII30</prot> . The
      binding of  <prot>hTAFII28</prot>  and  <prot>hTAFII30</prot>  requires distinct domains of   <prot>hTAFII18</prot>  . As
      observed with the homologous Drosophila proteins,  <prot>hTAFII20</prot>  interacts
      directly with  <prot>TBP</prot>;  however, additional interactions between   <prot>hTAFII20</prot>   and
       <prot>hTAFII28</prot>  or  <prot>hTAFII30</prot>  were detected. These results reveal differences not
      only in subunit composition, but also in the organization of <prot>dTFIID</prot> and
      <prot>hTFIID</prot> complexes.
AD  - Institut de Genetique et de Biologie Moleculaire et Cellulaire,
