title: "Splicing" of paramyosin filaments.
abstract: We have obtained electron micrographs of negatively stained thick filaments from the smooth adductor muscles of the oyster which show in detail the bipolar region of the paramyosin core. The polarity of the filament changes to either side of a line included at only 3 degrees to the filament axis. Along this line the pattern of interactions repeats every 8 X 14.4 nm. A model for the molecular organization is proposed. We conclude that this unusual arrangement occurs in order to maintain the tensile strength of the filament in the same way as the strength of a rope is maintained when joining two ends by a long splice.
mesh_terms: D000818:Animals; D046911:Macromolecular Substances; D008854:Microscopy, Electron; D009132:Muscles / Q000032:analysis; D010125:Ostreidae; D014335:Tropomyosin
chemical_list: D046911:Macromolecular Substances; D014335:Tropomyosin