Dephosphorylation of distinct sites on the 20 kDa myosin light chain by smooth muscle myosin phosphatase

FEBS Letters

Isaka, Naoki³  Feng, Jianhua³  Ito, Masaaki³  Hartshorne, David J¹  Nakano, Takeshi³  Nishikawa, Masakatsu²  Okinaka, Tsutomu³ 

[1] Muscle Biology Group, Shantz Building, University of Arizona, Tucson AZ 85721, USA;Second Department of Internal Medicine, Mie University School of Medicine, Tsu, Mie 514-8507, Japan;First Department of Internal Medicine, Mie University School of Medicine, Tsu, Mie 514-8507, Japan

关键词: Smooth muscle myosin;    Myosin light chain;    Myosin phosphatase;    Myosin light chain kinase;    Protein kinase C;    MP;    myosin phosphatase;    PP1;    type 1 protein phosphatase;    PP1cδ;    the δ isoform of the catalytic subunit of PP1;    PP2A;    type 2A protein phosphatase;    PP2Ac;    the catalytic subunit of PP2A;    MLCK;    myosin light chain kinase;    MLC20;    20 kDa myosin light chain;    PKC;    Ca2+-activated;    phospholipid-dependent protein kinase;    SDS;    sodium dodecyl sulfate;    PAGE;    polyacrylamide gel eletrophoresis;   

DOI  :  10.1016/S0014-5793(99)00337-3

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The dephosphorylation of the myosin light chain kinase and protein kinase C sites on the 20 kDa myosin light chain by myosin phosphatase was investigated. The myosin phosphatase holoenzyme and catalytic subunit, dephosphorylated Ser-19, Thr-18 and Thr-9, but not Ser-1/Ser-2. The role of non-catalytic subunits in myosin phosphatase was to activate the phosphatase activity. For Ser-19 and Thr-18, this was due to a decrease in K _m and an increase in k _cat and for Thr-9 to a decrease in K _m. Thus, the distinction between the various sites is a property of the catalytic subunit.

【 授权许可】

Unknown