Effects of phosphorylation and nucleotides on the conformation of myosin II from Acanthamoeba castellanii.

摘要: The actin-activated Mg(2+)-ATPase activity of filamentous Acanthamoeba myosin II is inactivated by phosphorylation a short non-helical tailpiece at the C-terminal end each heavy chain even though catalytic sites are in N-terminal globular head. Consistent with this effect, tip tail alters conformation head as shown shift principal site cleavage endoproteinase Arg-C (Ganguly, C., Martin, B., Bubb, M., and Korn, E. D. (1992) J. Biol. Chem. 267, 20905-20908). We now show that sedimentation coefficient monomeric phospho-myosin 1.3-4.6% lower than dephospho-myosin II, which suggests produces less compact small increase frictional coefficient. As changes papain digestion patterns, bound nucleotide also affects region phospho- II. Conformational differences between dephospho- phospho-forms presence nucleotide, detected susceptibility to proteolysis, therefore, appear be greater filaments monomers. These results provide additional evidence for communication heads tails