Myosin filament perpendicular

In setting up the coordinate system, the X-axis is taken parallel to the axis of the myosin filament the Y-axis is taken perpendicular to the myosin filament in the direction of the actin filament to which the cross-bridge would attach, and the Z-axis is approximated by sighting through the center of the a-helical sequence of the lever arm involving residues 825 to 800 of scallop muscle. 

View of Complete Cross-bridge in the YZ Plane Perpendicular to the Myosin Filament... 

As mentioned above, the junctional SR is connected to sheets of perpendicular SR (Fig. 4), which extend from the PM through a peripheral cytoplasmic region with lower myofilament density into the myoplasm. It is proposed that during the active state of wave-like [Ca2+]j oscillations, Ca2+ taken up by the junctional SR is released by these perpendicular sheets near the calmodulin, which is tethered to the myosin light chain kinase (MLCK) of the thin filaments (M. Walsh, personal communication, 2001). This process would enhance the specificity and efficiency of Ca2+ regulation of contraction. 

Due to symmetry in the plane perpendicular to the z-axis, we experimentally choose the optical propagation direction k perpendicular to the myosin/actin filament axis z (and incident field polarization e). In this case, we can control the incident field polarization E in both ordinary and extraordinary axis, which are perpendicular or parallel to the filament axis z respectively. By decomposing the induced SHG polarization into components parallel and perpendicular to the filament axis as... 

Figure 9A show the acquired SHG intensity dependency on the angle 6 between myosin/actin filaments orientation z and the incident fundamental polarization e. No polarizer was placed before the detection PMT. The arrow indicates the fundamental polarization direction e. It is interesting and straightforward to find that the maximum of SHG emission intensity does not occur as the myosin/actin filaments being parallel or perpendicular to the funda-... 

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