Mutants of smooth muscle myosin light chain kinase at tryptophan 800.
Mutants of smooth muscle myosin light chain kinase at tryptophan 800.
复制标题
平滑肌肌球蛋白轻链激酶色氨酸 800 的突变体。
DOI：
10.1006/bbrc.1994.2076
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发表时间：
1994
影响因子：
3.1
通讯作者：
Hartshorne,DJ
中科院分区：
文献类型：
--
作者：
Matsushima,S;Huang,YP;Dudas,CV;GuerrieroJr,V;Hartshorne,DJ
研究了Trp 800在肌球蛋白轻链激酶钙调蛋白结合部位的重要性。表达了Leu447到C末端的截断突变体。将Trp 800点突变为Gly、Cys、Leu和Tyr，对这些基因进行修饰。这个位置的色氨酸比其他任何残基都更有效。Leu突变体具有部分活性，其对钙调蛋白的Km从约10 nM降至175 nM。Tyr突变体具有可检测到的活性，但另外两个突变体没有活性，不结合钙调蛋白。因此，位置800的Trp是至关重要的。在高钙调素浓度下，Leu突变体的活性低于野生型突变体，约为20%。这表明，钙调蛋白的结合不会以全有或全无的机制释放抑制，其他分子内相互作用也是重要的。
The importance of Trp 800 in the calmodulin-binding site of myosin light chain kinase was investigated. Truncation mutants from Leu 447 to the C-terminus were expressed inE. coliand these were modified by point mutations of Trp 800 to Gly, Cys, Leu and Tyr. Trp at this position was more effective than any of the other residues. The Leu mutant was partially active and its Km for calmodulin decreased from about 10 nM to 175 nM. The Tyr mutant had detectable activity but the other two mutants were inactive and did not bind calmodulin. Thus Trp at position 800 is critical. The activity of the Leu mutant at high calmodulin concentrations was less than the wild-type mutant, about 20%. This suggests that the binding of calmodulin does not release inhibition in an all-or-none mechanism and that other intramolecular interactions are important.