Effects of the N-terminal domains of myosin binding protein-C in an in vitro motility assay

Evidence for long-lived cross-bridges

Maria V. Razumova, Justin F. Shaffer, An Yue Tu, Galina V. Flint, Michael Regnier, Samantha P. Harris

Research output: Contribution to journalArticle

83 Citations (Scopus)

Abstract

Myosin binding protein-C (MyBP-C) is a thick-filament protein whose precise function within the sarcomere is not known. However, recent evidence from cMyBP-C knock-out mice that lack MyBP-C in the heart suggest that cMyBP-C normally slows cross-bridge cycling rates and reduces myocyte power output. To investigate possible mechanisms by which cMyBP-C limits cross-bridge cycling kinetics we assessed effects of recombinant N-terminal domains of MyBP-C on the ability of heavy meromyosin (HMM) to support movement of actin filaments using in vitro motility assays. Here we show that N-terminal domains of cMyBP-C containing the MyBP-C "motif," a sequence of ∼110 amino acids, which is conserved across all MyBP-C isoforms, reduced actin filament velocity under conditions where filaments are maximally activated (i.e. either in the absence of thin filament regulatory proteins or in the presence of troponin and tropomyosin and high [Ca2+]). By contrast, under conditions where thin filament sliding speed is submaximal (i.e. in the presence of troponin and tropomyosin and low [Ca2+]), proteins containing the motif increased filament speed. Recombinant N-terminal proteins also bound to F-actin and inhibited acto-HMM ATPase rates in solution. The results suggest that N-terminal domains of MyBP-C slow cross-bridge cycling kinetics by reducing rates of cross-bridge detachment.

Original languageEnglish (US)
Pages (from-to)35846-35854
Number of pages9
JournalJournal of Biological Chemistry
Volume281
Issue number47
DOIs
StatePublished - Nov 24 2006
Externally publishedYes

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Assays
Myosin Subfragments
Actins
Tropomyosin
Amino Acid Motifs
Troponin
pioglitazone
Actin Cytoskeleton
Proteins
Sarcomeres
Kinetics
Knockout Mice
Muscle Cells
Adenosine Triphosphatases
myosin-binding protein C
In Vitro Techniques
Amino Acid Sequence
Protein Isoforms
Amino Acids

ASJC Scopus subject areas

  • Biochemistry

Cite this

Effects of the N-terminal domains of myosin binding protein-C in an in vitro motility assay : Evidence for long-lived cross-bridges. / Razumova, Maria V.; Shaffer, Justin F.; Tu, An Yue; Flint, Galina V.; Regnier, Michael; Harris, Samantha P.

In: Journal of Biological Chemistry, Vol. 281, No. 47, 24.11.2006, p. 35846-35854.

Research output: Contribution to journalArticle

Razumova, Maria V. ; Shaffer, Justin F. ; Tu, An Yue ; Flint, Galina V. ; Regnier, Michael ; Harris, Samantha P. / Effects of the N-terminal domains of myosin binding protein-C in an in vitro motility assay : Evidence for long-lived cross-bridges. In: Journal of Biological Chemistry. 2006 ; Vol. 281, No. 47. pp. 35846-35854.
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