Electron microscopic observations of negatively stained myosin minifilaments in a solution containing 10 mM-citrate buffer (pH 8.0), 4 mm-MgCl2 reveal ordered assemblies. They reveal bundles of parallel minifilaments of about 330 nm in length, aggregated into periodic linear and hexagonal structures. These structures are formed by means of interaction between myosin heads, arranged at the ends of minifilament bundles. The addition of 1 mm-ATP to the above solution causes dissociation of minifilament bundles into individual minifilaments without preventing the latter from association into linear "end-to-end" assemblies. Phosphorylation of myosin light chains does not exert any noticeable effect on the structure of the ordered minifilament assemblies but significantly increases their quantity. The interaction between minifilaments observed by us should be taken into consideration in studies on the properties of myosin which make use of minifilament systems.
ASJC Scopus subject areas
- Molecular Biology