Phosphorylation of troponin I by protein kinase C: mechanism of inhibition by calmodulin and troponin C.
Phosphorylation of troponin I by protein kinase C: mechanism of inhibition by calmodulin and troponin C.
复制标题
蛋白激酶 C 磷酸化肌钙蛋白 I：钙调蛋白和肌钙蛋白 C 的抑制机制。
DOI：
10.1016/0167-4889(87)90225-4
复制
发表时间：
1987
期刊：
影响因子：
--
通讯作者：
Nelsestuen,GL
中科院分区：
文献类型：
--
作者：
Bazzi,MD;Lampe,PD;Strasburg,GM;Nelsestuen,GL
研究了钙调蛋白和肌钙蛋白 C 通过蛋白激酶 C 影响肌钙蛋白 I (TnI) 磷酸化的机制。蛋白激酶 C 磷酸化 TnI 需要酸性磷脂、钙和二酰甘油的存在。光散射强度和荧光强度实验表明，TnI与磷脂膜结合并引起广泛聚集。在存在 Ca2+ 的情况下，大约化学计量的肌钙蛋白 C 或钙调蛋白可阻止 TnI-磷脂相互作用。肌钙蛋白 C 可完全抑制蛋白激酶 C 或磷酸化酶 b 激酶对 TnI 的磷酸化。相比之下，钙调蛋白完全抑制蛋白激酶C对TnI的磷酸化，但对磷酸化酶b激酶对TnI的磷酸化影响很小。钙调蛋白的抑制作用似乎并不是由于与 PKC 的相互作用，因为钙调蛋白轻微增加了组蛋白 III-S 的蛋白激酶 C 磷酸化。对于被克拉莫杜林抑制高达 90% 的反应，蛋白激酶 C 磷酸化 TnI 中磷酸丝氨酸与磷酸苏氨酸的比率保持大致恒定。高盐浓度也阻止了 TnI 与磷脂的相互作用以及 PKC 对 TnI 的磷酸化。然而，足以抑制磷酸化的盐浓度足以仅使 TnI 从膜上解离，而不能使蛋白激酶 C 从膜上解离。这些结果表明，TnI 与磷脂的结合是蛋白激酶 C 磷酸化所必需的，并且通过任何方式阻止这种结合都会完全抑制蛋白激酶 C 对 TnI 的磷酸化。
The mechanism by which calmodulin and troponin C influence phosphorylation of troponin I (TnI) by protein kinase C was investigated. The phosphorylation of TnI by protein kinase C requires the presence of acidic phospholipid, calcium and diacylglycerol. Light scattering intensity and fluorescence intensity experiments showed that TnI associated with the phospholipid membranes and caused extensive aggregation. In the presence of Ca2+, TnI-phospholipid interactions were prevented by approximately stoichiometric amounts of either troponin C or calmodulin. Troponin C was shown to completely inhibit phosphorylation of TnI by either protein kianse C or by phosphorylasebkinase. In contrast, calmodulin completely inhibited phosphorylation of TnI by protein kinase C, but had only little effect on TnI phosphorylation by phosphorylase b kinase. Inhibition by calmodulin did not appear to be due to interaction with PKC, since calmodulin mildly increased protein kinase C phosphorylation of histone III-S. The ratio of phosphoserine to phosphothreonine in protein kinase C-phosphorylated TnI remained approximately constant for reactions inhibited by up to 90% by clamodulin. TnI interactions with phospholipid and phosphorylation of TnI by PKC were also prevented by high salt concentrations. However, salt concentrations adequate to inhibit phosphorylation were sufficient to dissociate only TnI, but not protein kinase C from the membrane. These results suggest that the binding of TnI to phospholipid is required for phosphorylation by protein kinase C and that prevention of this binding by any means completely inhibited phosphorylation of TnI by protein kinase C.