TI  - Identification of interaction partners for the basic-helix-loop-helix
      protein <prot>E47</prot>.
PG  - 891-8
AB  - Helix-loop-helix proteins constitute a family of transcription factors
      with the potential to form homo- and hetero-dimers mediated by the
      helix-loop-helix domain. Oncogenic mutations in such genes can disrupt the
      equilibrium of protein-protein interactions in the affected cell. In order
      to assess the biological consequences of such mutations, the full
      complement of interacting proteins must be known. To identify proteins
      interacting with the basic-helix-loop-helix domain of the ubiquitously
      expressed <prot>E47</prot> protein, a 'sandwich'-screening procedure was developed
      which distinguishes between homo- and hetero-oligomers, and specifically
      excludes the detection of complexes which cannot bind DNA. Nine distinct
      cDNAs were identified which encode proteins with apparent
      basic-helix-loop-helix domains, including a novel clone termed <prot>eip1</prot> which
      is distantly related in the basic-helix-loop-helix domain to the
      Drosophila enhancer-of-split m7 protein. Using epitope-tagging,
      interaction of  <prot>E47</prot>  basic-helix-loop-helix protein with the  <prot>eip1</prot>  protein
      encoded by this novel cDNA was confirmed by immunoprecipitation
      experiments in COS7 cells. Interaction was also observed in the yeast
      two-hybrid system. Three cDNAs encoding proteins without
      basic-helix-loop-helix domains were also found to interact in the
      sandwich-expression screen. Interactions with human <prot>PARP</prot> and mouse
      <prot>replication factor 1a</prot> were confirmed using glutathione transferase-tagged
      cDNAs. A cDNA encoding part of the  <prot>nucleolin</prot>  protein sequence interacted
      with the  <prot>E47</prot>  basic-helix-loop-helix only when fused to a
      beta-galactosidase tag.
AD  - Deutsches Krebsforschungszentrum, Heidelberg, Germany.
