Document Detail

Myosin phosphatase: structure, regulation and function.
MedLine Citation:
PMID:  15124925     Owner:  NLM     Status:  MEDLINE    
Phosphorylation of myosin II plays an important role in many cell functions, including smooth muscle contraction. The level of myosin II phosphorylation is determined by activities of myosin light chain kinase and myosin phosphatase (MP). MP is composed of 3 subunits: a catalytic subunit of type 1 phosphatase, PPlc; a targeting subunit, termed myosin phosphatase target subunit, MYPT; and a smaller subunit, M20, of unknown function. Most of the properties of MP are due to MYPT and include binding of PP1c and substrate. Other interactions are discussed. A recent discovery is the existence of an MYPT family and members include, MYPT1, MYPT2, MBS85, MYPT3 and TIMAP. Characteristics of each are outlined. An important discovery was that the activity of MP could be regulated and both activation and inhibition were reported. Activation occurs in response to elevated cyclic nucleotide levels and various mechanisms are presented. Inhibition of MP is a major component of Ca2+-sensitization in smooth muscle and various molecular mechanisms are discussed. Two mechanisms are cited frequently: (1) Phosphorylation of an inhibitory site on MYPT1, Thr696 (human isoform) and resulting inhibition of PP1c activity. Several kinases can phosphorylate Thr696, including Rho-kinase that serves an important role in smooth muscle function; and (2) Inhibition of MP by the protein kinase C-potentiated inhibitor protein of 17 kDa (CPI-17). Examples where these mechanisms are implicated in smooth muscle function are presented. The critical role of RhoA/Rho-kinase signaling in various systems is discussed, in particular those vascular smooth muscle disorders involving hypercontractility.
Masaaki Ito; Takeshi Nakano; Ferenc Erdodi; David J Hartshorne
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.; Review    
Journal Detail:
Title:  Molecular and cellular biochemistry     Volume:  259     ISSN:  0300-8177     ISO Abbreviation:  Mol. Cell. Biochem.     Publication Date:  2004 Apr 
Date Detail:
Created Date:  2004-05-04     Completed Date:  2005-01-25     Revised Date:  2009-11-19    
Medline Journal Info:
Nlm Unique ID:  0364456     Medline TA:  Mol Cell Biochem     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  197-209     Citation Subset:  IM    
First Department of Internal Medicine, Mie University School of Medicine, Tsu, Mie, Japan.
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MeSH Terms
Calcium / metabolism
Cyclic GMP-Dependent Protein Kinases / genetics,  metabolism
Gene Expression Regulation, Developmental
Membrane Proteins / genetics,  metabolism
Muscle Contraction*
Muscle Proteins / genetics,  metabolism
Muscle, Smooth / enzymology*
Myosin Type II / chemistry,  genetics,  metabolism*
Myosin-Light-Chain Phosphatase / chemistry,  genetics,  metabolism*
Phosphoprotein Phosphatases / genetics,  metabolism
Phosphoproteins / genetics,  metabolism
Protein Phosphatase 1
Protein Subunits / genetics,  metabolism
Grant Support
Reg. No./Substance:
0/Membrane Proteins; 0/Muscle Proteins; 0/PPP1R14A protein, human; 0/PPP1R16B protein, human; 0/Phosphoproteins; 0/Protein Subunits; 7440-70-2/Calcium; EC GMP-Dependent Protein Kinases; EC Phosphatases; EC Phosphatase 1; EC Phosphatase; EC protein, human; EC 3.6.1.-/Myosin Type II

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