Leiomodin and tropomodulin in smooth muscle
Leiomodin and tropomodulin in smooth muscle
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DOI：
10.1152/ajpcell.2001.280.6.c1645
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发表时间：
2001-06-01
影响因子：
5.5
通讯作者：
Conley, CA
中科院分区：
文献类型：
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作者：
Conley, CA
越来越多的证据表明，肌动蛋白丝重塑是平滑肌收缩的关键，这意味着肌动蛋白丝末端是调节收缩的重要位点。通过蛋白质免疫印迹和免疫荧光显微镜，在许多含有平滑肌的组织中发现了原调节蛋白（Tmod）和平滑肌调节蛋白（SM-Lmod）。这两种蛋白质与原肌球蛋白在兔胃平滑肌的Triton不溶性细胞骨架中结合，并被高盐增溶。SM-Lmod结合肌肉原肌球蛋白，这是Tmod蛋白的生化活性特征。SM-Lmod染色沿着大鼠肠平滑肌中的肌动蛋白丝的长度存在，而Tmod以不同于肌动蛋白丝或致密体标记物α-辅肌动蛋白的点状图案染色。在通过用10 mM Ca 2+处理使平滑肌过度收缩后，发现SM-Lmod和Tmod都在富含肌动蛋白的收缩带的外周处的α-肌动蛋白附近。这些数据表明，SM-Lmod是平滑肌肌动蛋白细胞骨架的一个新的组成部分，此外，在平滑肌肌动蛋白丝的尖端可能被Tmod在本地集群。
Evidence is accumulating to suggest that actin filament remodeling is critical for smooth muscle contraction, which implicates actin filament ends as important sites for regulation of contraction. Tropomodulin (Tmod) and smooth muscle leiomodin (SM-Lmod) have been found in many tissues containing smooth muscle by protein immunoblot and immunofluorescence microscopy. Both proteins cofractionate with tropomyosin in the Triton-insoluble cytoskeleton of rabbit stomach smooth muscle and are solubilized by high salt. SM-Lmod binds muscle tropomyosin, a biochemical activity characteristic of Tmod proteins. SM-Lmod staining is present along the length of actin filaments in rat intestinal smooth muscle, while Tmod stains in a punctate pattern distinct from that of actin filaments or the dense body marker alpha -actinin. After smooth muscle is hypercontracted by treatment with 10 mM Ca2+, both SM-Lmod and Tmod are found near alpha -actinin at the periphery of actin-rich contraction bands. These data suggest that SM-Lmod is a novel component of the smooth muscle actin cytoskeleton and, furthermore, that the pointed ends of actin filaments in smooth muscle may be capped by Tmod in localized clusters.