Heavy meromyosin myosin interactions

It is of interest that the Si subfragment, the head of the myosin molecule, does not induce any aggregation in the presence of connectin (Maruyama et al., 1985a). However, heavy meromyosin interacted with connectin to form aggregates. The neck portion S2 of myosin did not act on connectin. L-Meromyosin and the rod portion of myosin were markedly... 

On the other hand, it has been suggested, based on immunopre-cipitation reactions, that CCT might interact with a broad range (accounting for 9-15%) of newly synthesized eukaryotic proteins (Feldman and Frydman, 2000 McCallum et al., 2000 Thulasiraman et al., 1999). There is also evidence that some proteins other than actins and tubulins fold via interaction with CCT. These include G -transducin (Farr etal, 1997), cyclinE (Won etal., 1998), and the von Hippel-Landau tumor suppressor protein VHL (Feldman et al., 1999). Moreover, translation in vitro of myosin heavy and light chains has identified an intermediate in the biogenesis of the heavy meromyosin subunit (HMM) of skeletal muscle myosin that contains all three myosin subunits and CCT, from which partially folded HMM can be released in an ATP-dependent reaction. Other as yet unknown cytosolic protein(s) are also apparently required for the completion of the myosin folding reaction (Srikakulam and Winkelmann, 1999). 

Figure 4.11 (a) Diagrammatic representation of the myosin filament and its interaction with the actin filament during the ATP hydrolysis cycle. More detail of the steps involved is given in section S.l. (b) Outline of the composition of the myosin molecule indicating the SI head of each chain, which contains both the active site for the ATPase reaction and the actin binding site. The proteolytic cleavage sites, a and b, are involved in the production SI and the double headed heavy meromyosin (HMM) respectively. 

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