Myosin phosphorylation decreases the ATPase activity of cardiac myofibrils.
Myosin phosphorylation decreases the ATPase activity of cardiac myofibrils.
复制标题
肌球蛋白磷酸化会降低心肌原纤维的 ATP 酶活性。
DOI：
10.1016/s0022-2828(84)80624-0
复制
发表时间：
1984
影响因子：
5
通讯作者：
Stull,JT
中科院分区：
文献类型：
--
作者：
Franks,K;Cooke,R;Stull,JT
我们以前的工作表明肌球蛋白磷酸化降低了用戊二醛轻度固定的骨骼肌肌原纤维的ATP酶活性。固定过程防止肌节缩短和破坏有序的细丝阵列后，加入ATP。我们现在已经将这些结果扩展到从兔、狗和大鼠心脏制备的肌原纤维。肌原纤维通过与肌球蛋白轻链激酶、钙调蛋白和ATP-γs或ATP在25°C下孵育15分钟而磷酸化。肌球蛋白轻链磷酸化程度为50%至80%。在0°C下与0.01%戊二醛反应5分钟，未磷酸化的肌原纤维的ATP酶活性没有改变，磷酸化也没有改变未固定的肌原纤维的ATP酶活性。磷酸化使固定肌原纤维的ATP酶活性降低50%。磷酸化对心肌肌原纤维ATP酶活性的影响在三种动物中相似。这些结果表明，在骨骼肌和心肌中，肌球蛋白磷酸化降低了跨桥循环的速率，导致能量消耗减少。肌球蛋白轻链磷酸化对ATP酶活性的影响似乎也需要有序的肌丝结构。
Our previous work showed that myosin phosphorylation decreased the ATPase activity of skeletal muscle myofibrils that were lightly fixed with glutaraldehyde. The fixation process prevented sarcomere shortening and destruction of the ordered filament array upon the addition of ATP. We have now extended these results to myofibrils prepared from hearts of rabbits, dogs and rats. Myofibrils were phosphorylated by incubation with myosin light chain kinase, calmodulin and either ATP-γs or ATP, for 15 minutes at 25°C. The extent of myosin light chain phosphorylation was 50% to 80%. The ATPase activity of unphosphorylated myofibrils was not altered by reaction with 0.01% glutaraldehyde for 5 minutes at 0°C, and the ATPase activity of unfixed myofibrils was not changed by phosphorylation. However, phosphorylation decreased the ATPase activity of fixed myofibrils by 50%. The effect on myocardial myofibrillar ATPase activity of phosphorylation was similar in the three animal species. These results suggest that in both skeletal and cardiac muscle, myosin phosphorylation decreases the rate of cross-bridge cycling resulting in decreased energy expenditure. It also appears that the effect of myosin light chain phosphorylation on ATPase activity requires an ordered myofilament structure.