The structure of the paramyosin filaments of various smooth muscles of Mytilus galloprovincialis has been studied by electron microscopy, with negative-stain technique. These filaments show a transverse period of 144 Å, and sometimes a unique superimposed dot-pattern, arranged to form a net structure. A helical structure can be excluded. The filaments do not appear flaked into ribbons. The tropomyosin A molecules are oriented parallel to the miofilament direction. A possible packing scheme for the paramyosin structure is proposed.
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Con il contributo del Ministero per i Beni e le Attività Culturali