Actin-dystrophin interface.

Dystrophin, an elongated cytoskeletal molecule which is deficient in Duchenne muscular disease, contains an actin-binding domain in its N-terminal portion. We show that this part interacted with actin in the native molecule. By molecular biology techniques, four recombinant proteins were expressed in Escherichia coli using the pMAL vector which allowed us to obtain soluble proteins directly after purification. These constructions were tested for their ability to bind actin under various conditions, and their apparent dissociation constants were determined. The effects of other actin-binding proteins such as caldesmon and tropomyosin were analyzed in comparison to the actin-binding properties of these constructions. These results support the potential concept of a multiple actin-binding contact in the N-terminal region of dystrophin. Differences in the functional domains are discussed relative to similar alpha-actinin-actin-binding sites.