Modification of Lys-237 on actin by 2,4-pentanedione. Alteration of the interaction of actin with tropomyosin.
Modification of Lys-237 on actin by 2,4-pentanedione. Alteration of the interaction of actin with tropomyosin.
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DOI：
10.1016/s0021-9258(18)90615-0
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发表时间：
1984-09
期刊：
影响因子：
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通讯作者：
S. El-Saleh;R. Thieret;P. Johnson;J. Potter
中科院分区：
文献类型：
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作者：
S. El-Saleh;R. Thieret;P. Johnson;J. Potter
它已经有可能特异性标记兔骨骼肌肌动蛋白在赖氨酸-237与2，4-戊二酮，产生烯胺。该反应可以用羟胺逆转。修饰可以用G-或F-形式的肌动蛋白进行，并且不影响聚合-解聚。然而，修饰确实影响原肌球蛋白（Tm）与修饰的F-肌动蛋白的相互作用。在不存在Ca 2+和Mg 2+（mu = 0.12）的情况下，Tm不能结合修饰的F-肌动蛋白，而它结合未修饰的F-肌动蛋白（1 Tm：7肌动蛋白）。在这些条件下，可通过加入肌钙蛋白（Tn）、Mg 2+或Mg 2+和Ca 2+来恢复Tm结合。在某些条件下，Tm单独已显示出抑制肌动蛋白激活的重质裂肌球蛋白（HMM）-Mg 2 +-ATP酶。这种抑制没有发生与修饰的F-肌动蛋白，即使Tm结合（约1 Tm：7肌动蛋白）。即使当Tn加入到该系统中（在没有Ca 2+的情况下），也不能观察到ATP酶的抑制。因此，这种修饰似乎阻止了F-肌动蛋白X Tm呈现“阻断”抑制位置（构象）。此外，无论Ca ~（2+）存在与否，Tn似乎都能增强修饰的F-actin X Tm复合物对重酶解肌球蛋白-Mg ~（2+）-ATP酶的激活。这种状态可以类似于增强状态（Murray，J.M.，Knox，M. K.，特鲁布拉德角E、和Weber，A.（1982）Biochemistry 27，906-915），在低ATP水平下观察到肌球蛋白亚片段1-饱和肌动蛋白。因此，使用修饰的和未修饰的F-肌动蛋白，可以产生三种Tm X肌动蛋白状态：关闭（F-肌动蛋白X Tm）、开启（修饰的F-肌动蛋白X Tm）和“增强”（修饰的F-肌动蛋白X Tm X Tn）。
It has been possible to specifically label rabbit skeletal muscle actin at Lys-237 with 2,4-pentanedione, producing an enamine. This reaction can be reversed with hydroxylamine. The modification can be carried out with actin in either the G- or F-forms and does not affect polymerization-depolymerization. The modification does affect, however, the interaction of tropomyosin (Tm) with the modified F-actin. In the absence of Ca2+ and Mg2+ (mu = 0.12), Tm failed to bind to the modified F-actin whereas it did bind to unmodified F-actin (1 Tm:7 actins). Tm binding could be restored under these conditions by the addition of either troponin (Tn), Mg2+, or Mg2+ and Ca2+. Under certain conditions, Tm alone has been shown to inhibit actin-activated heavy meromyosin (HMM)-Mg2+-ATPase. This inhibition did not occur with the modified F-actin even though Tm was bound (approximately 1 Tm:7 actins). Even when Tn was added to this system (in the absence of Ca2+), no inhibition of ATPase could be observed. Thus, this modification appears to prevent F-actin X Tm from assuming the “blocking” inhibitory position (conformation). In addition, Tn appears to enhance the activation of heavy meromyosin-Mg2+-ATPase by the modified F-actin X Tm complex whether Ca2+ is present or not. This state may be analogous to the potentiated state (Murray, J. M., Knox, M. K., Trueblood, C. E., and Weber, A. (1982) Biochemistry 27, 906-915) seen with myosin subfragment 1-saturated actin at low ATP levels. Thus, using modified and unmodified F-actin, it is possible to produce three Tm X actin states: off (F-actin X Tm), on (modified F-actin X Tm), and “potentiated” (modified F-actin X Tm X Tn).