TI  -  <prot>Syntrophin</prot>  binds to an alternatively spliced exon of  <prot>dystrophin</prot> .
PG  - 363-71
AB  - <prot>Dystrophin</prot>, the protein product of the Duchenne muscular dystrophy locus,
      is a protein of the membrane cytoskeleton that associates with a complex
      of integral and membrane-associated proteins. Of these, the 58-kD
      intracellular membrane-associated protein, syntrophin, was recently shown
      to consist of a family of three related but distinct genes. We expressed
      the cDNA of human <prot>beta 1-syntrophin</prot> and the COOH terminus of human
      <prot>dystrophin</prot> in reticulocyte lysates using an in vitro
      transcription/translation system. Using antibodies to <prot>dystrophin</prot> we
      immunoprecipitated these two interacting proteins in a variety of salt and
      detergent conditions. We demonstrate that the 53 amino acids encoded on
      exon 74 of  <prot>dystrophin</prot> , an alternatively spliced exon, are necessary and
      sufficient for interaction with translated  <prot>beta 1-syntrophin</prot>  in our assay.
      On the basis of its alternative splicing, <prot>dystrophin</prot> may thus be present
      in two functionally distinct populations. In this recombinant expression
      system, the <prot>dystrophin</prot> relatives,  human <prot><prot>dystrophin</prot> related protein</prot> (<prot>DRP</prot> or
      <prot>utrophin</prot>)  and the  <prot>87K postsynaptic protein</prot>  from Torpedo electric organ,
      also bind to translated   <prot>beta 1-syntrophin</prot>  . We have found a COOH-terminal
      37-kD fragment of  <prot>beta 1-syntrophin</prot>  sufficient to interact with translated
       <prot>dystrophin</prot>  and its homologues, suggesting that the  <prot>dystrophin</prot>  binding site
      on  <prot>beta 1-syntrophin</prot>  occurs on a region that is conserved among the three
      syntrophin homologues.
AD  - Program in Neuroscience, Harvard Medical School, Boston, Massachusetts
