Thin filament regulation and ionic interactions between the N-terminal region in actin and troponin.
Thin filament regulation and ionic interactions between the N-terminal region in actin and troponin.
复制标题
肌动蛋白和肌钙蛋白 N 端区域之间的细丝调节和离子相互作用。
DOI：
10.1016/s0006-3495(02)75282-x
复制
发表时间：
2002
影响因子：
3.4
通讯作者：
Reisler,Emil
中科院分区：
文献类型：
--
作者：
Wong,WeniseW;Gerson,JackH;Rubenstein,PeterA;Reisler,Emil
肌动蛋白的N端区域在跨桥周期和调节中与肌球蛋白和肌钙蛋白（Tn）相互作用。为了研究该区域在调控中的作用，我们使用了酸性残基数量增加和减少的酵母肌动蛋白突变体。突变体包括D24 A/D25 A，其中Asp 24和Asp 25被丙氨酸取代; DNEQ，其中Asp 2和Glu 4被其酰胺类似物取代;和4Ac，其中Glu 3和Asp 4插入代替Ser 3。在体外运动性测定中，使用重构的调节细丝，DNEQ、D24 A/D25 A和4Ac的滑动速度在所有pCa值下相似。因此，细丝的Ca 2+敏感性和TnI的抑制功能似乎对肌动蛋白N端电荷（±2）的变化不敏感，表明该肌动蛋白区域在调节中的作用很小（如果有的话）。一个Ca 2+独立的构象变化，在该地区的检测后，肌钙蛋白结合肌动蛋白-Tm通过增加荧光的芘探针连接到另一个酵母肌动蛋白突变体，我们使用（Cys 1）。
The N-terminal region in actin has been shown to interact with both myosin and troponin (Tn) during the cross-bridge cycle and in regulation. To study the role of this region in regulation, we used yeast actin mutants with increased and decreased numbers of acidic residues. The mutants included D24A/D25A, with Asp24and Asp25replaced with alanines; DNEQ, with the substitution of Asp2and Glu4with their amide analogs; and 4Ac, with Glu3and Asp4inserted in lieu of Ser3. In the in vitro motility assay, using reconstituted regulated thin filaments, the sliding speeds of DNEQ, D24A/D25A, and 4Ac were similar at all pCa values. Thus, Ca2+-sensitivity of the thin filaments and the inhibitory function of TnI appear to be insensitive to changes in charge (±2) at the N-terminus of actin, suggesting little, if any, role of that actin region in regulation. A Ca2+-independent conformational change in that region was detected upon troponin binding to actin-Tm via an increase in the fluorescence of a pyrene probe attached to another yeast actin mutant that we used (Cys1).