The myosin-binding protein C motif binds to F-actin in a phosphorylation-sensitive manner

Justin F. Shaffer, Robert W. Kensler, Samantha P. Harris

Research output: Contribution to journalArticle

128 Citations (Scopus)

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 (Kd) of ∼10 μM and a molar binding ratio (Bmax) near 1.0, indicating 1:1 (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 Bmax) and eliminated actin cross-linking. These results suggest that theNterminus 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 crossbridge cycling.

Original languageEnglish (US)
Pages (from-to)12318-12327
Number of pages10
JournalJournal of Biological Chemistry
Volume284
Issue number18
DOIs
StatePublished - May 1 2009

Fingerprint

Amino Acid Motifs
Phosphorylation
Actins
Cardiac Myosins
Connectin
Myosins
myosin-binding protein C
Actomyosin
Sarcomeres
Actin Cytoskeleton
Light scattering
Electron microscopy
Assays
Electron Microscopy
Binding Sites
Light

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Molecular Biology

Cite this

The myosin-binding protein C motif binds to F-actin in a phosphorylation-sensitive manner. / Shaffer, Justin F.; Kensler, Robert W.; Harris, Samantha P.

In: Journal of Biological Chemistry, Vol. 284, No. 18, 01.05.2009, p. 12318-12327.

Research output: Contribution to journalArticle

Shaffer, Justin F. ; Kensler, Robert W. ; Harris, Samantha P. / The myosin-binding protein C motif binds to F-actin in a phosphorylation-sensitive manner. In: Journal of Biological Chemistry. 2009 ; Vol. 284, No. 18. pp. 12318-12327.
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