van der Ven P F, Obermann W M, Lemke B, Gautel M, Weber K, Fürst D O
University of Potsdam, Department of Cell Biology, Potsdam, Germany.
Cell Motil Cytoskeleton. 2000 Feb;45(2):149-62. doi: 10.1002/(SICI)1097-0169(200002)45:2<149::AID-CM6>3.0.CO;2-G.
Filamin, also called actin binding protein-280, is a dimeric protein that cross-links actin filaments in the cortical cytoplasm. In addition to this ubiquitously expressed isoform (FLN1), a second isoform (ABP-L/gamma-filamin) was recently identified that is highly expressed in mammalian striated muscles. A monoclonal antibody was developed, that enabled us to identify filamin as a Z-disc protein in mammalian striated muscles by immunocytochemistry and immunoelectron microscopy. In addition, filamin was identified as a component of intercalated discs in mammalian cardiac muscle and of myotendinous junctions in skeletal muscle. Northern and Western blots showed that both, ABP-L/gamma-filamin mRNA and protein, are absent from proliferating cultured human skeletal muscle cells. This muscle specific filamin isoform is, however, up-regulated immediately after the induction of differentiation. In cultured myotubes, ABP-L/gamma-filamin localises in Z-discs already at the first stages of Z-disc formation, suggesting that ABP-L/gamma-filamin might play a role in Z-disc assembly.
细丝蛋白，也称为肌动蛋白结合蛋白-280，是一种二聚体蛋白，可使皮质细胞质中的肌动蛋白丝交联。除了这种普遍表达的异构体（FLN1）外，最近还鉴定出第二种异构体（ABP-L/γ-细丝蛋白），它在哺乳动物横纹肌中高度表达。我们开发了一种单克隆抗体，通过免疫细胞化学和免疫电子显微镜，使我们能够将细丝蛋白鉴定为哺乳动物横纹肌中的Z盘蛋白。此外，细丝蛋白被鉴定为哺乳动物心肌闰盘和骨骼肌肌腱连接的组成部分。Northern印迹和Western印迹显示，增殖的培养人骨骼肌细胞中不存在ABP-L/γ-细丝蛋白mRNA和蛋白。然而，这种肌肉特异性细丝蛋白异构体在诱导分化后立即上调。在培养的肌管中，ABP-L/γ-细丝蛋白在Z盘形成的最初阶段就定位于Z盘，这表明ABP-L/γ-细丝蛋白可能在Z盘组装中起作用。
