The reconstruction of myosin filaments in rabbit psoas muscle from solubilized myosin.

Using rabbit psoas muscle strips, A-bands with their myosin-containing thick filaments have been substantially reconstructed in situ (as judged by electron and light microscopy and by low-angle X-ray diffraction analysis) after prior solubilization of the myosin filaments in high ionic strength potassium phosphate solution. The maintenance of a very high local concentration of soluble myosin, by means of a closely apposed artificial semi-permeable membrane is necessary for reconstruction of full-length filaments. This reconstruction effect can be totally abolished by pre-glycerolation of the muscle, or (reversibly) by pre-depletion of Ca2+. Reconstruction at longer sarcomere lengths (greater than 2.6 micron) is anomalous, part-length 'stub filaments' being formed, with their stub tails projecting out from the I-Z-I lattice. A model is proposed to explain this reconstruction effect.