title: Single actomyosin motor interactions in skeletal muscle.
abstract: 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 1:10(5). 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.
authors.affiliation: Department of Molecular Biology and Immunology, University of North Texas Health Science Center, 3500 Camp Bowie Boulevard, Fort Worth, TX 76107, USA. Zeno.Foldes-Papp@medunigraz.at
authors.forename: Zeno
authors.initials: Z
authors.lastname: Földes-Papp
authors.forename: Shih-Chu Jeff
authors.initials: SC
authors.lastname: Liao
authors.forename: Ben
authors.initials: B
authors.lastname: Barbieri
authors.forename: Karol
authors.initials: K
authors.lastname: Gryczynski
authors.forename: Rafal
authors.initials: R
authors.lastname: Luchowski
authors.forename: Zygmunt
authors.initials: Z
authors.lastname: Gryczynski
authors.forename: Ignacy
authors.initials: I
authors.lastname: Gryczynski
authors.forename: Julian
authors.initials: J
authors.lastname: Borejdo
authors.forename: Tiefeng
authors.initials: T
authors.lastname: You
mesh_terms: D000205:Actomyosin / Q000378:metabolism*; D000818:Animals; D005454:Fluorescence Polarization; D005456:Fluorescent Dyes / Q000378:metabolism; D020409:Molecular Motor Proteins / Q000378:metabolism*; D009119:Muscle Contraction / Q000502:physiology; D009127:Muscle Rigidity / Q000503:physiopathology; D018482:Muscle, Skeletal / Q000378:metabolism*; D011485:Protein Binding; D011817:Rabbits; D013997:Time Factors
chemical_list: D005456:Fluorescent Dyes; D020409:Molecular Motor Proteins; D000205:Actomyosin