Regulation of the filament structure and assembly of Acanthamoeba myosin II by phosphorylation of serines in the heavy-chain nonhelical tailpiece

Significance Class II myosins are the only members of this superfamily of actin-associated molecular motors that form antiparallel bipolar filaments, which are essential for the biological functions of these myosins. Here we show that the assembly of Acanthamoeba myosin II monomers into minifilaments is modified by phosphorylation of one or more of four serine residues in the 27-residue nonhelical tailpiece at the end of each of the two heavy chains that form the coiled-coil helix characteristic of class II myosins. This regulatory mechanism might be applicable to other class II myosins that have a nonhelical tailpiece.