Abstract

Previous studies had strongly indicated that phosphorylation of the heavy chains of Acanthamoeba myosin II inactivated its actin-activated ATPase activity by altering the conformation of the myosin II filaments. By developing new assay procedures, it has been possible to keep myosin II monomeric and thus demonstrate that, in contrast to filamentous myosin II, phosphorylated monomeric myosin II retains full enzymatic activity. This result supports the conclusion that regulation of myosin II by phosphorylation occurs at the level of the filament. Immunofluorescence and immunoelectron microscopy have shown the myosin I heavy chain kinase is strongly localized to the plasma membrane. Kinase binds with high affinity to plasma membranes. The C-terminal half of the kinase contains about half of the total phosphorylation sites, these are still autophosphorylatable, and autophosphorylation enhances the myosin I kinase activity of the fragment. However, in contrast to the native enzyme, autophosphorylation of the fragment is not enhanced by acidic phospholipids.

  Funding Agency

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Intramural Research (Z01)
Project #
1Z01HL000506-16
Application #
3857976
Study Section
Project Start
Project End
Budget Start
Budget End
Support Year
16
Fiscal Year
1991
Total Cost
Indirect Cost

  Institution

Name
National Heart, Lung, and Blood Institute
Department
Type
DUNS #
City
State
Country
United States
Zip Code

  Publications

Baek, Kyuwon; Liu, Xiong; Ferron, Francois et al. (2008) Modulation of actin structure and function by phosphorylation of Tyr-53 and profilin binding. Proc Natl Acad Sci U S A 105:11748-53
Hwang, Kae-Jung; Mahmoodian, Fatemeh; Ferretti, James A et al. (2007) Intramolecular interaction in the tail of Acanthamoeba myosin IC between the SH3 domain and a putative pleckstrin homology domain. Proc Natl Acad Sci U S A 104:784-9
Szczepanowska, Joanna; Korn, Edward D; Brzeska, Hanna (2006) Activation of myosin in HeLa cells causes redistribution of focal adhesions and F-actin from cell center to cell periphery. Cell Motil Cytoskeleton 63:356-74
Liu, Xiong; Shu, Shi; Hong, Myoung-Soon S et al. (2006) Phosphorylation of actin Tyr-53 inhibits filament nucleation and elongation and destabilizes filaments. Proc Natl Acad Sci U S A 103:13694-9
Shu, Shi; Mahadeo, Dana C; Liu, Xiong et al. (2006) S-adenosylhomocysteine hydrolase is localized at the front of chemotaxing cells, suggesting a role for transmethylation during migration. Proc Natl Acad Sci U S A 103:19788-93
Shu, Shi; Liu, Xiong; Korn, Edward D (2005) Blebbistatin and blebbistatin-inactivated myosin II inhibit myosin II-independent processes in Dictyostelium. Proc Natl Acad Sci U S A 102:1472-7
Liu, Xiong; Shu, Shi; Kovacs, Mihaly et al. (2005) Biological, biochemical, and kinetic effects of mutations of the cardiomyopathy loop of Dictyostelium myosin II: importance of ALA400. J Biol Chem 280:26974-83
Ishikawa, Takashi; Cheng, Naiqian; Liu, Xiong et al. (2004) Subdomain organization of the Acanthamoeba myosin IC tail from cryo-electron microscopy. Proc Natl Acad Sci U S A 101:12189-94
Korn, Edward D (2004) The discovery of unconventional myosins: serendipity or luck? J Biol Chem 279:8517-25
Brzeska, Hanna; Szczepanowska, Joanna; Matsumura, Fumio et al. (2004) Rac-induced increase of phosphorylation of myosin regulatory light chain in HeLa cells. Cell Motil Cytoskeleton 58:186-99

Showing the most recent 10 out of 21 publications