دورية
Dual Regulation of Mammalian Myosin VI Motor Function*
| العنوان: | Dual Regulation of Mammalian Myosin VI Motor Function* |
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| المؤلفون: | Yoshimura, Misako, Homma, Kazuaki, Saito, Junya, Inoue, Akira, Ikebe, Reiko, Ikebe, Mitsuo |
| المصدر: | Journal of Biological Chemistry; October 2001, Vol. 276 Issue: 43 p39600-39607, 8p |
| مستخلص: | Myosin VI is expressed in a variety of cell types and is thought to play a role in membrane trafficking and endocytosis, yet its motor function and regulation are not understood. The present study clarified mammalian myosin VI motor function and regulation at a molecular level. Myosin VI ATPase activity was highly activated by actin with Kactinof 9 µm. A predominant amount of myosin VI bound to actin in the presence of ATP unlike conventional myosins.KATPwas much higher than those of other known myosins, suggesting that myosin VI has a weak affinity or slow binding for ATP. On the other hand, ADP markedly inhibited the actin-activated ATPase activity, suggesting a high affinity for ADP. These results suggested that myosin VI is predominantly in a strong actin binding state during the ATPase cycle. p21-activated kinase 3 phosphorylated myosin VI, and the site was identified as Thr406. The phosphorylation of myosin VI significantly facilitated the actin-translocating activity of myosin VI. On the other hand, Ca2+diminished the actin-translocating activity of myosin VI although the actin-activated ATPase activity was not affected by Ca2+. Calmodulin was not dissociated from the heavy chain at high Ca2+, suggesting that a conformational change of calmodulin upon Ca2+binding, but not its physical dissociation, determines the inhibition of the motility activity. The present results revealed the dual regulation of myosin VI by phosphorylation and Ca2+binding to calmodulin light chain. |
| قاعدة البيانات: | Supplemental Index |
| تدمد: | 00219258 1083351X |
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| DOI: | 10.1074/jbc.M105080200 |