The identification of a new actin-binding region in p57

The actin-binding protein p57 is a member of mammalian coronin-like proteins. The roles of this protein in phagocytic processes conceivably depend on its interactions with F-actin. Two regions, p57(1-34) and p57(111-204), were previously reported to be actin-binding sites. In this study, we found that the C-terminal region of p57, p57(297-461), also possessed F-actin binding activity. Furthermore, the leucine zipper domain at the C-terminus of p57(297-461) was essential for this actin-binding activity. The F-actin cross-linking assay revealed that the region contained in p57(297-461) was sufficient to cross-link actin filaments. Our results strongly suggested that there was a new actin-binding region at the C-terminus of p57.