TI  - The POU domains of the  <prot>Oct1</prot>  and  <prot>Oct2</prot>  transcription factors mediate
      specific interaction with   <prot>TBP</prot>  .
PG  - 1655-62
AB  - We had previously shown that the ubiquitous <prot>Oct1</prot> and the lymphoid-specific
      <prot>Oct2</prot> transcription factors stimulate transcription at the level of stable
      preinitiation complex formation. We have therefore investigated whether
      the octamer binding proteins might physically interact with <prot>TBP</prot>, the <prot>TATA
      box binding protein</prot> component of the <prot>TFIID</prot> factor. By using several
      different experimental systems we show that   <prot>TBP</prot>   efficiently associates
      with  <prot>Oct1</prot>  and  <prot>Oct2</prot> . The interaction is direct and does not depend on the
      presence of DNA or additional proteins. N- and C-terminal deletions of the
      different proteins were used to localize the domains involved in the
      interaction. We show that the POU homeodomain of <prot>Oct2</prot> and the
      evolutionarily conserved C-terminal core domain of <prot>TBP</prot> are both required
      and sufficient for the interaction. The  <prot>Oct1</prot> POU domain , which is highly
      homologous to the <prot>Oct2</prot> POU domain, likewise mediates interaction with  <prot>TBP</prot> .
      The interaction can also be observed in vivo, as  <prot>TBP</prot>  can be
      co-precipitated with  <prot>Oct2</prot>  from co-transfected Cos1 cells and  <prot>TBP</prot> 
      co-immunoprecipitates with the endogenous  <prot>Oct1</prot>  from HeLa cells.
      Co-transfection of human <prot>TBP</prot> and <prot>Oct2</prot> expression vectors into B cells
      resulted in a synergistic activation of an octamer motif containing
      promoter.
AD  - Zentrum fur Molekulare Biologie Heidelberg, Germany.
