TI  - Interaction of the regulatory subunit (<prot>RII</prot>) of <prot>cAMP-dependent protein
      kinase</prot> with <prot>RII</prot>-anchoring proteins occurs through an amphipathic helix
      binding motif.
PG  - 14188-92
AB  - The  <prot>type II cAMP-dependent protein kinase</prot>  is localized to specific
      subcellular environments through the binding of the regulatory subunit
      (<prot>RII</prot>) dimer to  <prot>RII</prot>-anchoring proteins . Computer-aided analysis of
      secondary structure, performed on four <prot>RII</prot>-anchoring protein sequences
      (the <prot>microtubule-associated protein 2</prot>, <prot>P150</prot>, and two thyroid proteins <prot>Ht
      21</prot> and <prot>Ht 31</prot>), has identified common regions of approximately 14 residues
      which display high probabilities of forming amphipathic helices. The
      potential amphipathic helix region of <prot>Ht 31</prot>
      (Leu-Ile-Glu-Glu-Ala-Ala-Ser-Arg-Ile-Val-Asp-Ala-Val-Ile) lies between
      residues 494 and 507. A bacterially expressed 318-amino acid fragment,  <prot>Ht
      31</prot>  (418-736), containing the amphipathic helix region, was able to bind
       <prot><prot>RII</prot> alpha</prot>. Site-directed mutagenesis designed to disrupt the secondary
      structure in the putative binding helix reduced binding dramatically.
      Specifically, substitution of proline for Ala-498 significantly diminished
      <prot><prot>RII</prot> alpha</prot> binding, and similar mutation of Ile-502 or Ile-507 abolished
      interaction. Mutation of Ala-522 to proline, which is located outside the
      predicted amphipathic helix region, had no effect on <prot><prot>RII</prot> alpha</prot> binding.
      These data suggest that anchoring proteins interact with <prot><prot>RII</prot> alpha</prot> via an
      amphipathic helix binding motif.
AD  - Vollum Institute for Advanced Biomedical Research, Oregon Health Sciences
