钙调蛋白与肌动蛋白羧基末端的相互作用。
The interaction of caldesmon with the COOH terminus of actin.
作者信息
Crosbie R, Adams S, Chalovich J M, Reisler E
机构信息
Department of Chemistry and Biochemistry, University of California, Los Angeles 90024.
出版信息
J Biol Chem. 1991 Oct 25;266(30):20001-6.
Caldesmon interacts with the NH2-terminal region of actin. It is now shown in airfuge centrifugation experiments that modification of the penultimate cysteine residue of actin significantly weakens its binding to caldesmon both in the presence and absence of tropomyosin. Furthermore, as revealed by fluorescence measurements, caldesmon increases the exposure of the COOH-terminal region of actin to the solvent. This effect of caldesmon, like its inhibitory effect on actomyosin ATPase activity, is enhanced in the presence of tropomyosin. Proteolytic removal of the last three COOH-terminal residues of actin, containing the modified cysteine residue, restores the normal binding between caldesmon and actin. These results establish a correlation between the binding of caldesmon to actin and the conformation of the COOH-terminal region of actin and suggest an indirect rather than direct interaction between caldesmon and this part of actin.
钙调蛋白与肌动蛋白的氨基末端区域相互作用。现在通过空气离心机实验表明，肌动蛋白倒数第二个半胱氨酸残基的修饰在有和没有原肌球蛋白的情况下均会显著削弱其与钙调蛋白的结合。此外，荧光测量结果显示，钙调蛋白增加了肌动蛋白羧基末端区域向溶剂的暴露。钙调蛋白的这种作用，与其对肌动球蛋白ATP酶活性的抑制作用一样，在有原肌球蛋白存在时会增强。用蛋白酶去除肌动蛋白最后三个羧基末端残基（其中包含修饰的半胱氨酸残基）可恢复钙调蛋白与肌动蛋白之间的正常结合。这些结果建立了钙调蛋白与肌动蛋白结合以及肌动蛋白羧基末端区域构象之间的相关性，并表明钙调蛋白与肌动蛋白的这一部分之间是间接而非直接相互作用。
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