title: Size and localization of dystrophin molecule: immunoelectron microscopic and freeze etching studies of muscle plasma membranes of murine skeletal myofibers.
abstract: The ultrastructure and mode of existence of the dystrophin molecule and its relations to actin filaments were examined in murine skeletal myofibers. Electron microscopy of freeze-etched replicas of gold-labelled dystrophin molecules in quick-freeze, deep-etch, rotary-shadow preparations revealed rod-like structures 108.2 +/- 16.3 nm long and 3.1 +/- 1.5 nm thick. Some dystrophin molecules appeared to link their ends to form anastomosing networks; others were separate from each other. The dystrophin molecules were parallel or nearly parallel to the inner surface of the muscle plasma membrane. Double immuno-labelling transmission electron microscopy using N- and C-terminal dystrophin antibodies showed that the group mean distances of the N- and C-terminal signals from the muscle plasma membrane were 52.7 +/- 8.1 nm and 45.9 +/- 11.3 nm, respectively, which were not significantly different. Histograms of the distribution of the N- and C-terminal distances from the muscle plasma membrane had similar patterns with peaks 10-20 nm from the membrane. This was consistent with the findings of the mode of existence of dystrophin molecules seen in freeze-etched replicas. Finally, the dystrophin molecules were linked with the most peripheral sarcoplasmic actin like filaments, end to side as well as end to end.
authors.affiliation: Department of Medicine, Showa University Fujigaoka Hospital, Yokohama, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Wakayama
authors.forename: S
authors.initials: S
authors.lastname: Shibuya
authors.forename: T
authors.initials: T
authors.lastname: Jimi
authors.forename: A
authors.initials: A
authors.lastname: Takeda
authors.forename: H
authors.initials: H
authors.lastname: Oniki
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies; D015153:Blotting, Western; D002462:Cell Membrane / Q000473:pathology / Q000648:ultrastructure*; D016189:Dystrophin / Q000032:analysis*; D005613:Freeze Etching; D051379:Mice; D008810:Mice, Inbred C57BL; D008818:Mice, Neurologic Mutants; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D009132:Muscles / Q000473:pathology / Q000648:ultrastructure*; D009137:Muscular Dystrophy, Animal / Q000473:pathology*; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000276:immunology; D011817:Rabbits / Q000276:immunology
chemical_list: D000906:Antibodies; D016189:Dystrophin; D010446:Peptide Fragments