The essential light chain is required for full force production by skeletal muscle myosin.
Proc Natl Acad Sci U S A
; 91(26): 12403-7, 1994 Dec 20.
Article
em En
| MEDLINE
| ID: mdl-7809049
ABSTRACT
Myosin, a molecular motor that is responsible for muscle contraction, is composed of two heavy chains each with two light chains. The crystal structure of subfragment 1 indicates that both the regulatory light chains (RLCs) and the essential light chains (ELCs) stabilize an extended alpha-helical segment of the heavy chain. It has recently been shown in a motility assay that removal of either light chain markedly reduces actin filament sliding velocity without a significant loss in actin-activated ATPase activity. Here we demonstrate by single actin filament force measurements that RLC removal has little effect on isometric force, whereas ELC removal reduces isometric force by over 50%. These data are interpreted with a simple mechanical model where subfragment 1 behaves as a torque motor whose leyer arm length is sensitive to light-chain removal. Although the effect of removing RLCs fits within the confines of this model, altered crossbridge kinetics, as reflected in a reduced unloaded duty cycle, probably contributes to the reduced velocity and force production of ELC-deficient myosins.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Actomiosina
/
Miosinas
/
Contração Muscular
Limite:
Animals
Idioma:
En
Revista:
Proc Natl Acad Sci U S A
Ano de publicação:
1994
Tipo de documento:
Article