Axial Dispositions and Conformations of Myosin Crossbridges Along Thick Filaments in Relaxed and Contracting States of Vertebrate Striated Muscles by X-ray Fiber Diffraction

Structural dependence of HET-s amyloid fibril infectivity assessed by cryoelectron microscopy

“…Finally, we observed an apparent pairing of subunits along the fibril. The significance of this pairing is not evident, although we note that similar effects have been observed in some other protein filaments: tobacco mosaic virus (23), SH3 amyloid (24), the mammalian prion protein PrP (25), and myosin (26).…”

Direct visualization of myosin-binding protein C bridging myosin and actin filaments in intact muscle

“…S1). "Forbidden" meridional reflections, at the first, second, and fourth orders of 43 nm come from the nonmyosin stripes and perturbations in the myosin helix (24)(25)(26).…”

“…Our studies do not address what happens during contraction. Weakening of the 44.2 nm MyBP-C X-ray reflection on contraction suggests that MyBP-C may become much more mobile in this state (26). One possibility is that binding to S2 occurs transiently by switching with actin during filament sliding.…”

Neutron diffraction measurements of skeletal muscle using the contrast variation technique: Analysis of the equatorial diffraction patterns

“…The perturbation of the axial repeat of myosin crowns is much reduced in the transition of muscle into the rigor state (Haselgrove, 1975;Malinchik and Lednev, 1992). The change in the backbone structure occurring in this transition suggests that it could be related to outward, protruding movements of the S2 region (subfragment 2 of heavy meromyosin), which lies closely on the surface of the backbone in the relaxed state (Stewart and Kensler, 1986;Oshima et al, 2007), and thereby bringing the myosin heads closer to the thin filament. During this process, hydration/dehydration of the backbone might occur as changes in hydration by protein dissociation/association affect the partial specific volume of the protein (Chalikian, 2003).…”

“…However, these peaks, particularly the peak corresponding to the first order layer line (M1) and that corresponding to the second order layer line (M2), arise from groups of closely spaced reflections that are fused together. The M1 reflection primarily consists of the peak arising from C-protein and the first peak from the troponin repeat (Rome et al, 1973a,b;Juanhuix et al, 2001;Oshima et al, 2007). The M2 reflection consists of a group of the reflections including C-protein reflections sampled by the centro-symmetric structure of the thick filaments at the M-line and the second peak from the troponin repeat (Rome et al, 1973b;Haselgrove, 1975;Juanhuix et al, 2001;Oshima et al, 2007).…”