Document Detail

Actin and light chain isoform dependence of myosin V kinetics.
MedLine Citation:
PMID:  11087368     Owner:  NLM     Status:  MEDLINE    
Recent studies on myosin V report a number of kinetic differences that may be attributed to the different heavy chain (chicken vs mouse) and light chain (essential light chains vs calmodulin) isoforms used. Understanding the extent to which individual light chain isoforms contribute to the kinetic behavior of myosin V is of critical importance, since it is unclear which light chains are bound to myosin V in cells. In addition, all studies to date have used alpha-skeletal muscle actin, whereas myosin V is in nonmuscle cells expressing beta- and gamma-actin. Therefore, we characterized the actin and light chain dependence of single-headed myosin V kinetics. The maximum actin-activated steady-state ATPase rate (V(max)) of a myosin V construct consisting of the motor domain and first light chain binding domain is the same when either of two essential light chain isoforms or calmodulin is bound. However, with bound calmodulin, the K(ATPase) is significantly higher and there is a reduction in the rate and equilibrium constants for ATP hydrolysis, indicating that the essential light chain favors formation of the M. ADP.P(i) state. No kinetic parameters of myosin V are strongly influenced by the actin isoform. ADP release from the actin-myosin complex is the rate-limiting step in the ATPase cycle with all actin and light chain isoforms. We postulate that although there are significant light-chain-dependent alterations in the kinetics that could affect myosin V processivity in in vitro assays, these differences likely are minimized under physiological conditions.
E M De La Cruz; A L Wells; H L Sweeney; E M Ostap
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Biochemistry     Volume:  39     ISSN:  0006-2960     ISO Abbreviation:  Biochemistry     Publication Date:  2000 Nov 
Date Detail:
Created Date:  2000-12-12     Completed Date:  2001-01-11     Revised Date:  2009-11-19    
Medline Journal Info:
Nlm Unique ID:  0370623     Medline TA:  Biochemistry     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  14196-202     Citation Subset:  IM    
University of Pennsylvania School of Medicine, Department of Physiology, Pennsylvania Muscle Institute, 3700 Hamilton Walk, Philadelphia, Pennsylvania 19104-6085, USA.
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MeSH Terms
Actins / metabolism,  physiology*
Adenosine Diphosphate / analogs & derivatives*,  metabolism
Adenosine Triphosphate / metabolism,  pharmacology
Amino Acid Motifs
Anthranilic Acids / metabolism
Calmodulin-Binding Proteins / metabolism*,  physiology
Muscle, Skeletal / metabolism,  physiology
Myosin Light Chains / metabolism,  physiology*
Myosin Type V*
Myosins / metabolism
Nerve Tissue Proteins / metabolism*,  physiology
Protein Binding
Protein Isoforms / metabolism,  physiology
Spectrometry, Fluorescence
Grant Support
Reg. No./Substance:
0/Actins; 0/Anthranilic Acids; 0/Calmodulin-Binding Proteins; 0/Myosin Light Chains; 0/Nerve Tissue Proteins; 0/Protein Isoforms; 0/chicken brain myosin-V p190; 56-65-5/Adenosine Triphosphate; 58-64-0/Adenosine Diphosphate; 73-22-3/Tryptophan; 85287-55-4/3'-O-(N-methylanthraniloyl)adenosine 5'-diphosphate; EC 3.6.1.-/Myosin Type V; EC

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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