Paramyosin and the filaments of molluscan “catch” muscles

The three-dimensional packing of molecules cannot be inferred, these results provide new information on the local packing relations of the molecules: 2-fold screw axes relate molecules—at least locally—in neighboring rows in a paramyosin filament

Carolyn Cohen

2004

Key concepts

Scholarcy highlights

  • Aggregates of paramyosin precipitated with divalent cations show a variety of forms with simple staining patterns and a period of 725 Å in the electron microscope
  • All the forms may be generated from a basic polar array where the molecules do not bond end-to-end: dark staining regions represent “gap” areas where stain can penetrate the paracrystal; light regions are “overlap” areas where stain is largely excluded
  • The molecular length deduced from the band patterns is about 1275 Å, and is slightly different in paramyosins from different sources
  • Since the same basic arrays are found in paramyosins from different sources, there are similar specific interaction sites on these molecules
  • The “nodes” of the native net patterns can be interpreted as the dark staining gaps of the polar form, and the native net pattern can be generated by a regular shift of groups of molecules or subfilaments in the basic polar array
  • The tendency of paramyosin to form both polar and bipolar arrays has led to the prediction of bipolarity in the native filament

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