MARCKS(myristoylated alanine-rich C kinase substrate), a major PKC substrate, is known to crosslink filamentous actin. The roles of MARCKS on the actin crosslinking were examined. Various MARCKS derivatives were prepared to determine the domains responsible for crosslinking actin filaments. The effects of MARCKS on the cross-linking of actin were examined by cosedimentation study and viscometric analysis. MARCKS derivatives containing lysine-rich phosphorylation domain were cosedimented with actin. These derivatives also increased viscosity of solution containing actin filaments. The present study suggested that MARCKS contains one actin binding site, lysine-rich phosphorylation domain.
