title: Characterization of the interaction between Actinin-Associated LIM Protein (ALP) and the rod domain of alpha-actinin.
abstract: BACKGROUND
  The PDZ-LIM proteins are a family of signalling adaptors that interact with the actin cross-linking protein, alpha-actinin, via their PDZ domains or via internal regions between the PDZ and LIM domains. Three of the PDZ-LIM proteins have a conserved 26-residue ZM motif in the internal region, but the structure of the internal region is unknown.
  
  
  RESULTS
  In this study, using circular dichroism and nuclear magnetic resonance (NMR), we showed that the ALP internal region (residues 107-273) was largely unfolded in solution, but was able to interact with the alpha-actinin rod domain in vitro, and to co-localize with alpha-actinin on stress fibres in vivo. NMR analysis revealed that the titration of ALP with the alpha-actinin rod domain induces stabilization of ALP. A synthetic peptide (residues 175-196) that contained the N-terminal half of the ZM motif was found to interact directly with the alpha-actinin rod domain in surface plasmon resonance (SPR) measurements. Short deletions at or before the ZM motif abrogated the localization of ALP to actin stress fibres.
  
  
  CONCLUSIONS
  The internal region of ALP appeared to be largely unstructured but functional. The ZM motif defined part of the interaction surface between ALP and the alpha-actinin rod domain.
authors.affiliation: Department of Biological and Environmental Science and Nanoscience Center, University of Jyväskylä, PO Box 35, 40014 Jyväskylä, Finland. tuula.klaavuniemi@oulu.fi
authors.forename: Tuula
authors.initials: T
authors.lastname: Klaavuniemi
authors.forename: Nanna
authors.initials: N
authors.lastname: Alho
authors.forename: Pirta
authors.initials: P
authors.lastname: Hotulainen
authors.forename: Annina
authors.initials: A
authors.lastname: Kelloniemi
authors.forename: Heli
authors.initials: H
authors.lastname: Havukainen
authors.forename: Perttu
authors.initials: P
authors.lastname: Permi
authors.forename: Sampo
authors.initials: S
authors.lastname: Mattila
authors.forename: Jari
authors.initials: J
authors.lastname: Ylänne