抄録
Contractile protein (myosin B) was isolated from myxoamoebae (haploid vegetative phase) of Physarum polycephalum. Myxoamoeba myosin B showed properties similar to those of natural actomyosin (myosin B) from muscle. Myxoamoeba myosin B appeared similar to myosin B of smooth muscle and non-muscle cells than to that of skeletal muscle, on the basis of quantitative characteristics and presence of only two light chains.
Myosin B isolated from myxoamoebae had almost the same properties asmyosin B from plasmodia (diploid vegetative phase of Physarum). On SDS-gel electrophoresis, identical to actin and myosin subunits of myxoamoeba werethose of the plasmodium. The apparent particle length of myxoamoeba myosin B was 0.62 to 0.55 μm, which was shorter than that of natural muscle actomyosin. Short length particles were also observed in plasmodium preparations. Some differences in ATPase activity were observed between myxoamoeba and plasmodium.
