title: Involvement of tail domains in regulation of Dictyostelium myosin II.
abstract: The actin-dependent ATPase activity of Dictyostelium myosin II filaments is regulated by phosphorylation of the regulatory light chain. Four deletion mutant myosins which lack different parts of subfragment 2 (S2) showed phosphorylation-independent elevations in their activities. Phosphorylation-independent elevation in the activity was also achieved by a double point mutation to replace conserved Glu932 and Glu933 in S2 with Lys. These results suggested that inhibitory interactions involving the head and S2 are required for efficient regulation. Regulation of wild-type myosin was not affected by copolymerization with a S2 deletion mutant myosin in the same filaments. Furthermore, the activity linearly correlated with the fraction of phosphorylated molecules in wild-type filaments. These latter two results suggest that the inhibitory head-tail interactions are primarily intramolecular.
authors.affiliation: Biomolecular Research Group, National Institute for Advanced Interdisciplinary Research, Ibaraki, Tsukuba, 305-8562, Japan.
authors.forename: X
authors.initials: X
authors.lastname: Liu
authors.forename: K
authors.initials: K
authors.lastname: Ito
authors.forename: R J
authors.initials: RJ
authors.lastname: Lee
authors.forename: T Q
authors.initials: TQ
authors.lastname: Uyeda
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D017301:Ca(2+) Mg(2+)-ATPase / Q000378:metabolism; D002478:Cells, Cultured; D004023:Dictyostelium / Q000737:chemistry*; D004591:Electrophoresis, Polyacrylamide Gel; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000378:metabolism; D008954:Models, Biological; D008969:Molecular Sequence Data; D009154:Mutation; D009218:Myosins / Q000737:chemistry* / Q000235:genetics; D010766:Phosphorylation; D017354:Point Mutation; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid
chemical_list: D008164:Luminescent Proteins; D049452:Green Fluorescent Proteins; D000251:Adenosine Triphosphatases; D017301:Ca(2+) Mg(2+)-ATPase; D009218:Myosins