Association of calponin with desmin intermediate filaments
Association of calponin with desmin intermediate filaments
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DOI：
10.1074/jbc.272.36.22662
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发表时间：
1997-09-05
影响因子：
4.8
通讯作者：
Tao, T
中科院分区：
文献类型：
--
作者：
Mabuchi, K;Li, B;Tao, T
我们之前对鸡胗平滑肌细胞的免疫电镜研究表明，在某些区域，抗钙钙蛋白的分布与-肌动蛋白、丝蛋白，特别是desmin高度重叠，这表明原位钙钙蛋白的一部分可能与细胞骨架的中间纤维有关。在这项工作中，我们通过研究钙钙蛋白和desmin之间的相互作用进一步探讨了这一观点。我们发现在生理盐浓度下，钙钙蛋白仅与合成的聚乳酸中间丝结合较弱。另一方面，钙钙蛋白与非丝状四聚体紧密结合，在含有6 M尿素的缓冲液中混合，并在含有0.15 M NaCl的缓冲液中透析时，钙钙蛋白与非丝状四聚体结合并被纳入中间丝状结构。从砂囊组织中分离出一部分中间细丝和致密体，可见抗钙钙蛋白的标记。我们的研究结果表明，在鸡胗平滑肌细胞中，钙钙蛋白可能是致密体附近的desmin中间丝的一个组成部分。由于钙钙蛋白也已知与肌动蛋白结合，我们假设钙钙蛋白的功能之一可能是在致密体中连接中间丝和肌动蛋白。
Our previous immunoelectron microscopy studies of chicken gizzard smooth muscle cells showed that in certain areas the distribution of anti-calponin exhibits a high degree of overlap with beta-actin, filamin, and in particular, desmin, suggesting that in situ a fraction of calponin may be associated with intermediate filaments of the cytoskeleton. In this work we further explore this idea by studying the interaction between calponin and desmin. We found that at physiological salt concentrations, calponin bound only weakly to synthetic desmin intermediate filaments. On the other hand, calponin bound strongly to nonfilamentous desmin tetramers and was incorporated into intermediate filaments when the two proteins were mixed in a buffer containing 6 M urea and dialyzed into a buffer containing 0.15 M NaCl. Anti-calponin was found to label a portion of intermediate filaments and dense bodies isolated from gizzard tissues. Our findings suggest that in chicken gizzard smooth muscle cells, calponin may be an integral component of desmin intermediate filaments in the vicinity of dense bodies. Since calponin is also known to bind actin, we hypothesize that one of the functions of calponin might be to bridge intermediate filaments with actin in dense bodies.