Selbert S, Fischer P, Menke A, Jockusch H, Pongratz D, Noegel A A
Max-Planck-Institut für Biochemie, Martinsried, Federal Republic of Germany.
Exp Cell Res. 1996 Jan 10;222(1):199-208. doi: 10.1006/excr.1996.0025.
Annexin VII (synexin) is a member of the annexin family of proteins, which are characterized by Ca(2+)-dependent binding to phospholipids. In normal skeletal muscle annexin VII is located preferentially at the plasma membrane and the t-tubule system [Selbert et al. (1995) J. Cell. Sci. 108, 85-95]. Here we have analyzed the distribution of annexin VII in muscle disorders in which the Ca2+ regulation is affected. A remarkable difference was observed in muscle specimens from patients suffering from Duchenne muscular dystrophy and also in muscle from the MDX mouse where annexin VII was gradually released from the sarcolemmal membrane into the cytosol and into the extracellular space during progression of the disease. Hypercontracted muscle fibers positive in Ca2+ staining were devoid of cytosolic annexin VII. Annexins IV and VI were similarly released into the extracellular space. Whereas normal skeletal muscle showed specifically the 51-kDa annexin VII isoform, in dystrophic muscle different ratios of the 51-kDa and the muscle-atypic 47-kDa isoforms were observed. The potential of annexin VII to serve as a tool with which cellular Ca2+ levels can be studied and different muscular disorders classified is discussed.
膜联蛋白VII（凝溶蛋白）是膜联蛋白家族的成员之一，该家族蛋白的特点是能依赖钙离子结合磷脂。在正常骨骼肌中，膜联蛋白VII主要位于质膜和横管系统[塞尔伯特等人（1995年）《细胞科学杂志》108卷，85 - 95页]。在此，我们分析了膜联蛋白VII在钙离子调节受影响的肌肉疾病中的分布情况。在患有杜兴氏肌营养不良症患者的肌肉标本以及MDX小鼠的肌肉中观察到了显著差异，在疾病进展过程中，膜联蛋白VII从肌膜逐渐释放到细胞质和细胞外空间。钙离子染色呈阳性的过度收缩肌纤维中没有细胞质膜联蛋白VII。膜联蛋白IV和VI也同样释放到细胞外空间。正常骨骼肌中特异性显示的是51 kDa的膜联蛋白VII异构体，而在营养不良的肌肉中，观察到了51 kDa和肌肉非典型47 kDa异构体的不同比例。本文讨论了膜联蛋白VII作为研究细胞钙离子水平和分类不同肌肉疾病工具的潜力。
