Single actomyosin motor interactions in skeletal muscle

Zeno Földes-Papp, Shih Chu Jeff Liao, Ben Barbieri, Karol Gryczynski, Rafal Luchowski, Zygmunt Gryczynski, Ignacy Gryczynski, Julian Borejdo, Tiefeng You

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1 Scopus citations


We present a study of intramuscular motion during contraction of skeletal muscle myofibrils. Myofibrillar actin was labeled with fluorescent dye so that the ratio of fluorescently labeled to unlabeled protein was 1:105. Such sparse labeling assured that there was on average only one actin-marker present in the focus at a given time. From the intensity signal in the two orthogonal detection channels, significant fluctuations, similar to fluorescent burst in diffusion-based single-molecule detection schemes, were identified via a threshold algorithm and analyzed with respect to their intensity and polarization. When only rigor complexes were formed, the fluctuations of polarized intensity were characterized by unimodal Gaussian photon distributions. During contraction, in contrast, bimodal Gaussian photon distributions were observed above the rigor background threshold. This suggests that the bimodal Gaussian photon distributions represent pre- and post-power stroke conformations. Clusters of polarized photons indicated an anisotropy decay of single actomyosin motors of ~9s during muscle contraction. This article is part of a Special Issue entitled: 11th European Symposium on Calcium.

Original languageEnglish
Pages (from-to)858-866
Number of pages9
JournalBiochimica et Biophysica Acta - Molecular Cell Research
Issue number5
StatePublished - May 2011


  • Live skeletal muscle cell
  • Molecular orientations
  • Polarization dependent fluorescence fluctuations
  • Single actomyosin
  • Time-dependent photon distributions


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