Structural relationships of actin-binding proteins.

The sequences of a large number of actin-binding proteins have been compared. These findings, together with the results of protein-chemical analysis, peptide synthesis and site-directed and deletion mutagenesis, have led to the assignment of actin-binding sites. Within these segments, small actin-binding motifs have been delineated. Most actin-binding proteins interact with actin subdomain-1 but our analyses reveal neither primary nor secondary structure homology among these proteins, suggesting that actin binding does not follow simple structural principles.