T. Hijikata et al., The direct visualization of structural array from laminin to dystrophin insarcolemmal vesicles prepared from rat skeletal muscles, BIO CELL, 90(9), 1998, pp. 629-639
It has been biochemically shown that dystrophin and alpha- and beta-dystrog
lycan form an oligomeric complex which links laminin, a component of the ba
sement membrane, to components of the subsarcolemmal cytoskeleton in skelet
al muscle fibers. In the present study the dystrophin-glycoprotein complex
and its structural relationships to laminin and subsarcolemmal cytoskeleton
were ultrastructurally examined in crude surface membranes prepared from r
at skeletal muscles. Sarcolemmal vesicles within crude surface membranes we
re identified and characterized by fine protrusions on their outer surface
and electron-dense materials or patches associated with the inner surface.
These two components were seen to be in register with each other across the
sarcolemma. The fine protrusions were immunolabeled by anti-alpha-dystrogl
ycan and reassociated with exogenous laminin. Immunolabeling in combination
with laminin reassociation demonstrated that the electron-dense materials
contained dystrophin at laminin-binding domains of the membrane. In additio
n, they were often associated with very fine filaments. These results provi
de morphological evidence for the biochemically proposed model of molecular
array of dystrophin complex from the basement membrane to the subsarcolemm
al cytoskeleton. ((C) Elsevier, Paris).