Papponen Hinni, Kaisto Tuula, Leinonen Sanna, Kaakinen Mika, Metsikkö Kalervo
Institute of Biomedicine, Department of Anatomy and Cell Biology, P.O. Box 5000 (Aapistie 7), FIN-90014 University of Oulu, Finland.
Exp Cell Res. 2009 Jan 15;315(2):218-25. doi: 10.1016/j.yexcr.2008.10.021. Epub 2008 Oct 31.
We investigated the targeting of the gamma-actin isoform in skeletal myofibers. For this purpose we used expression vectors to produce green fluorescent protein (GFP-) as well as myc-tagged gamma-actin in rat flexor digitorum brevis myofibers. We found that the gamma-actin fusion proteins accumulated into Z discs but not beneath the sarcolemma. Instead, the GFP-tagged skeletal muscle-specific alpha-actin isoform was preferentially incorporated into the pointed ends of thin contractile filaments. The localization pattern of the gamma-actin fusion proteins was completely different from that of the dystrophin glycoprotein complex on the sarcolemma. The results emphasize the role of gamma-actin as a Z disc component but fail to reveal an actin-based sub-sarcolemmal cytoskeleton in skeletal muscle cells.
我们研究了γ-肌动蛋白异构体在骨骼肌纤维中的靶向作用。为此，我们使用表达载体在大鼠趾短屈肌纤维中产生绿色荧光蛋白（GFP-）以及带有myc标签的γ-肌动蛋白。我们发现γ-肌动蛋白融合蛋白积聚在Z盘，但不在肌膜下方。相反，带有GFP标签的骨骼肌特异性α-肌动蛋白异构体优先整合到细收缩丝的尖端。γ-肌动蛋白融合蛋白的定位模式与肌膜上的肌营养不良蛋白糖蛋白复合物完全不同。这些结果强调了γ-肌动蛋白作为Z盘成分的作用，但未能揭示骨骼肌细胞中基于肌动蛋白的肌膜下细胞骨架。
