Differences between Smooth and Skeletal Muscle Myosins in Their Interactions with F-Actin
1982 年 91 巻 3 号 p. 1001-1007
詳細
1982 年 91 巻 3 号 p. 1001-1007
Myosin and F-actin were prepared from bovine carotid arterial smooth muscle and the properties of the binding of myosin to F-actin were compared with those of the binding of skeletal muscle myosin to F-actin. The following differences were observed between skeletal and smooth muscle myosins.
1. The rate of ATP-induced dissociation of arterial actomyosin was equal to that of hybrid actomyosin reconstituted from arterial myosin and skeletal muscle F-actin, but was much lower than those of skeletal muscle actomyosin and of hybrid actomyosin reconstituted from skeletal muscle myosin and arterial F-actin.
2. The amount of ATP necessary for complete dissociation of arterial actomyosin was 2 mol/mol of myosin, although it is well known that skeletal muscle actomyosin is dissociated completely by the addition of 1 mol ATP per mol of myosin.
3. Arterial actomyosin and hybrid actomyosin reconstituted from arterial myosin and skeletal muscle F-actin did not dissociate upon addition of 0.1mM PPi, while skeletal muscle actomyosin dissociated completely.
4. In the absence of Mg2+, neither dissociation by ATP nor ATPase [EC 3. 6. 1. 3] activity was observed with arterial actomyosin and hybrid actomyosin reconstituted from arterial myosin and skeletal muscle F-actin. On the other hand, skeletal muscle actomyosin dissociated almost completely upon addition of ATP and showed a considerably high ATPase activity.
These observations reveal marked differences between myosins from skeletal and smooth muscles in their binding properties to F-actin.
