The myosin-binding protein C motif binds to F-actin in a phosphorylation-sensitive manner.
J Biol Chem
; 284(18): 12318-27, 2009 May 01.
Article
em En
| MEDLINE
| ID: mdl-19269976
ABSTRACT
Cardiac myosin-binding protein C (cMyBP-C) is a regulatory protein expressed in cardiac sarcomeres that is known to interact with myosin, titin, and actin. cMyBP-C modulates actomyosin interactions in a phosphorylation-dependent way, but it is unclear whether interactions with myosin, titin, or actin are required for these effects. Here we show using cosedimentation binding assays, that the 4 N-terminal domains of murine cMyBP-C (i.e. C0-C1-m-C2) bind to F-actin with a dissociation constant (K(d)) of approximately 10 microm and a molar binding ratio (B(max)) near 1.0, indicating 11 (mol/mol) binding to actin. Electron microscopy and light scattering analyses show that these domains cross-link F-actin filaments, implying multiple sites of interaction with actin. Phosphorylation of the MyBP-C regulatory motif, or m-domain, reduced binding to actin (reduced B(max)) and eliminated actin cross-linking. These results suggest that the N terminus of cMyBP-C interacts with F-actin through multiple distinct binding sites and that binding at one or more sites is reduced by phosphorylation. Reversible interactions with actin could contribute to effects of cMyBP-C to increase cross-bridge cycling.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Sarcômeros
/
Proteínas de Transporte
/
Actinas
/
Miocárdio
Tipo de estudo:
Diagnostic_studies
Limite:
Animals
Idioma:
En
Revista:
J Biol Chem
Ano de publicação:
2009
Tipo de documento:
Article
País de afiliação:
Estados Unidos