Document Detail


Proximity of regulatory light chains in scallop myosin.
MedLine Citation:
PMID:  3159905     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The distance between the regulatory light chains of the two heads of the scallop myosin molecule was estimated with the aid of two photolabile cross-linkers, benzophenone maleimide and p-azidophenacylbromide. These cross-linkers selectively alkylate thiol groups and have a maximum length of about 9 A. One of the two regulatory light chains of scallop myosin was removed by treatment of myofibrils at 10 degrees C with EDTA and replaced with a foreign regulatory light chain carrying a cross-linker. Cross-linking between the scallop and foreign regulatory light chains was effected by photolysis. This was demonstrated by incubating nitrocellulose transfers of sodium dodecyl sulfate/polyacrylamide gels of the photolyzed hybrid myofibrils with specific antibodies against the different light chains, followed by fluorescein isothiocyanate-125I-labeled secondary antibody. Scallop regulatory light chains cross-linked extensively (20 to 50%) with Mercenaria regulatory light chains (cysteine in position approximately 50) in solutions that induce rigor in skinned fibers (no ATP) and in relaxing solutions (ATP but no Ca2+). Neither the regulatory light chains of chicken skeletal myosin (cysteines 129 and 157) nor those of gizzard myosin (cysteine 108) were cross-linked to scallop regulatory light chains in either medium. These results indicate that the N-terminal portions of the myosin regulatory light chains can approach each other within 9 A or less, while the distance between the C-terminal halves exceeds 9 A, and support the view that the N termini of the regulatory light chains point toward the myosin rod. Since the relative distance between the regulatory light chains of the two myosin heads is not altered between rigor and rest, we suggest that motion of the essential light chains is mainly responsible for the observed difference in the relative positions of the regulatory and essential light chains between conditions of rigor and rest.
Authors:
P M Hardwicke; A G Szent-Györgyi
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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.    
Journal Detail:
Title:  Journal of molecular biology     Volume:  183     ISSN:  0022-2836     ISO Abbreviation:  J. Mol. Biol.     Publication Date:  1985 May 
Date Detail:
Created Date:  1985-08-19     Completed Date:  1985-08-19     Revised Date:  2009-11-19    
Medline Journal Info:
Nlm Unique ID:  2985088R     Medline TA:  J Mol Biol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  203-11     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Adenosine Triphosphatases
Animals
Ca(2+) Mg(2+)-ATPase
Chickens
Cross-Linking Reagents
Electrophoresis, Polyacrylamide Gel
Immunoglobulin G
Mollusca
Myofibrils
Myosins*
Photolysis
Grant Support
ID/Acronym/Agency:
AM15963/AM/NIADDK NIH HHS; B.R.S.G. 6781//PHS HHS
Chemical
Reg. No./Substance:
0/Cross-Linking Reagents; 0/Immunoglobulin G; EC 3.6.1.-/Adenosine Triphosphatases; EC 3.6.1.-/Ca(2+) Mg(2+)-ATPase; EC 3.6.4.1/Myosins

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


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