Institute of Anatomy and Cell Biology, University of Freiburg, Albertstrasse 23, 79104, Freiburg, Germany.
Cell Tissue Res. 2010 Aug;341(2):313-23. doi: 10.1007/s00441-010-1003-7. Epub 2010 Jul 6.
Gelsolin was localized by immunoelectron microscopy in fast and slow cross-striated muscles of the lobster Homarus americanus. When ultrathin sections of the muscles were labelled with anti-gelsolin and a gold-conjugated second antibody, 90% of all gold particles in the myoplasm were detected on myofibrils, preferentially in the I-band and AI-region of the sarcomeres. Both the region of the H-zone (lacking thin filaments) and the Z-disc contained no or little gold label. Under physiological conditions, a close association of gelsolin with the thin filaments was observed for both muscle types. The preferential localization of particles in the I- and AI-region indicated that gelsolin was distributed randomly over the whole length of the thin filaments. Preincubation of muscle strips with Ringer solution containing 0.5 mM EGTA resulted in a significantly different distribution pattern; gold particles were now localized preferentially in the cell periphery close to the sarcolemma, with significantly decreased abundance in the centre of the cell. Compared with the muscle under physiological conditions, the number of gold particles over sarcomeric structures was significantly reduced. Thus, binding of gelsolin to the thin filaments is apparently reversible in vivo and depends on the presence of calcium ions. We assume a functional role for gelsolin in the actin turnover processes in invertebrate muscle systems.
免疫电子显微镜将凝胶蛋白定位于美洲螯龙虾的快肌和慢肌横纹肌中。当用抗凝胶蛋白和金结合的第二抗体标记肌肉的超薄切片时，肌浆中 90%的金颗粒都位于肌原纤维上，优先位于肌节的 I 带和 AI 区。H 带（缺乏细肌丝）和 Z 盘既没有或很少有金标记。在生理条件下，两种肌肉类型都观察到凝胶蛋白与细肌丝的紧密结合。颗粒在 I 带和 AI 区的优先定位表明凝胶蛋白随机分布在整个细肌丝的长度上。用含有 0.5 mM EGTA 的 Ringer 溶液预孵育肌条会导致明显不同的分布模式；金颗粒现在优先定位于靠近肌膜的细胞外周，细胞中心的丰度显著降低。与生理条件下的肌肉相比，肌节结构上的金颗粒数量明显减少。因此，凝胶蛋白与细肌丝的结合在体内显然是可逆的，并依赖于钙离子的存在。我们假设凝胶蛋白在无脊椎动物肌肉系统的肌动蛋白周转过程中具有功能作用。
