Troponin T is capable of binding dystrophin via a leucine zipper

Using genetic and physical assays for protein-protein interactions, we identified a fast isoform of troponin T that binds to dystrophin. Troponin T specifically bound to the first of two highly conserved leucine zipper motifs in the carboxy terminus of dystrophin [1,2]. Single amino acid changes in the zipper predicted to disrupt alpha-helix formation or cause steric hindrance abolished this binding. These data support the hypothesis that dystrophin couples the contractile apparatus to the sarcolemma and indicate that leucine zipper mediated protein-protein interactions are functionally important in the cytoskeleton as well as the nucleus.