An electron microscopic study of myofilament calcium binding sites in native, EGTA-chelated and calcium reloaded glycerolated mammalian skeletal muscle

1974 ◽  
Vol 14 (1) ◽  
pp. 139-152 ◽  
Author(s):  
Walter L. Davis ◽  
J. L. Matthews ◽  
J. H. Martin
1980 ◽  
Vol 185 (1) ◽  
pp. 265-268 ◽  
Author(s):  
J Wikman-Coffelt

The non-specific Ca2+-binding sites of skeletal-muscle myosin are located on the light chains; with the dissociation of light chains there is a corresponding decrease in the number of Ca2+-binding sites on light-chain-deficient myosin. The released light chains have a decreased binding affinity. Myosin heavy chains indirectly influence the Ca2+-binding properties of light chains by increasing the affinity of light chains for bivalent cations; this influence varies with pH. Because of light-chain dissociation at low Ca2+ and/or Mg2+ concentrations, anomalies may exist when analyses of non-specific Ca2+-binding properties of myosin are assessed by dialysis equilibrium.


1962 ◽  
Vol 13 (2) ◽  
pp. 323-335 ◽  
Author(s):  
G. G. Knappeis ◽  
F. Carlsen

This electron microscopic study deals with the structure of the Z disc of frog's skeletal muscle, with special regard to the I filaments—whether they pass through the Z disc or terminate at it. In most longitudinal sections the I filaments terminate as rod-like projections on either side of the Z disc, one I filament on one side lying between two I filaments on the opposite side. This indicates that the I filaments are not continuous through the Z disc. The rod-like projections are often seen to consist of filaments (denoted as Z filaments) which meet at an angle. In cross-sections through the Z region the I filaments and Z filaments form tetragonal patterns. The I filaments are situated in the corners of the squares; the oblique Z filaments form the sides of squares. The tetragonal pattern formed by the Z filaments is rotated 45 degrees with respect to the tetragons formed by the I filaments on both sides of Z. This structural arrangement is interpreted to indicate that each I filament on one side of the Z disc faces the center of the space between four I filaments on the opposite side of Z and that the interconnection is formed by four Z filaments.


PEDIATRICS ◽  
1966 ◽  
Vol 37 (2) ◽  
pp. 249-259
Author(s):  
Robert Darrell Cardiff

1. A case of Pompe's disease (glycogenosis II) without biochemically or histochemically demonstrable alpha-glucosidase activity is described. 2. Histochemical studies of skeletal muscle suggested that the glycogen is frequently stored as an acid mucopolysaccharide. 3. Electron microscopic studies revealed that the major glycogen deposits in most tissue were within membrane-limited sacs. Striated muscle was an exception because major deposits were frequently extrasaccular. 4. The findings in this case are discussed in relation to current concepts of Pompe's disease. In view of the extrasaccular glycogen deposits in skeletal muscle, it is suggested that an extralysosomal factor plays a significant role in the pathogenesis of Pompe's disease.


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