Vorovikov Iu S, Szczesna D, Kakol I
Biokhimiia. 1989 Jun;54(6):1041-5.
The structural state of tropomyosin (TM) modified by 5-(iodoacetamidoethyl)-aminonaphthalene-1-sulfonate (1.5-IAEDANS) upon F-actin decoration with myosin subfragment 1 (S1) and heavy meromyosin (HMM) in glycerinated myosin- and troponin-free muscle fibers was studied. HMM preparations contained native phosphorylated myosin light chains, while S1 preparations did not. The changes in the polarized fluorescence of 1.5-IAEDANS-TM during the F-actin interaction with S1 were independent of light chains phosphorylation and Ca2+ concentration, but were dependent on these factors during the F-actin interaction with HMM. The binding of myosin heads to F-actin is supposed to initiate conformational changes in TM which are accompanied by changes in the flexibility and molecular arrangement of TM. In the presence of light chains, the structural changes in TM depend on light chains phosphorylation and Ca2+ concentration. The conformational changes in TM seem to be responsible for the mechanisms of coupling of the myosin and tropomyosin modulation system during the actin-myosin interaction in skeletal muscles.
研究了在无肌球蛋白和肌钙蛋白的甘油化肌纤维中，用肌球蛋白亚片段1（S1）和重酶解肌球蛋白（HMM）装饰F-肌动蛋白时，5-（碘乙酰胺基乙基）-氨基萘-1-磺酸盐（1.5-IAEDANS）修饰的原肌球蛋白（TM）的结构状态。HMM制剂含有天然磷酸化的肌球蛋白轻链，而S1制剂则没有。在F-肌动蛋白与S1相互作用期间，1.5-IAEDANS-TM的偏振荧光变化与轻链磷酸化和Ca2+浓度无关，但在F-肌动蛋白与HMM相互作用期间则取决于这些因素。肌球蛋白头部与F-肌动蛋白的结合被认为会引发TM的构象变化，这些变化伴随着TM的柔韧性和分子排列的改变。在存在轻链的情况下，TM的结构变化取决于轻链磷酸化和Ca2+浓度。TM的构象变化似乎是骨骼肌中肌动蛋白-肌球蛋白相互作用期间肌球蛋白和原肌球蛋白调节系统偶联机制的原因。
