Molecular analysis of the interaction between palladin and α-actinin

Palladin is a novel component of stress fiber dense regions. Antisense and transient overexpression studies have indicated an important role for palladin in the regulation of actin cytoskeleton. Palladin colocalizes; and coinimunoprecipitates with alpha-actinin, a dense region component, but the molecular details and functional significance of the interaction have not been studied. We show here a direct association between the two proteins and have mapped the binding site within a short sequence of palladin and in the carboxy-terminal calmodulin domain of alpha-actinin. Using transfection-based targeting assays, we show that palladin is involved in targeting of a-actinin to specific subcellular foci indicating a functional interplay between the two actin-associated proteins. (C) 2004 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.