Characterization of muscle filamin isoforms suggests a possible role of ?-filamin/ABP-L in sarcomeric Z-disc formation
✍ Scribed by van der Ven, Peter F. M. ;Obermann, Wolfgang M. J. ;Lemke, Britt ;Gautel, Mathias ;Weber, Klaus ;F�rst, Dieter O.
- Book ID
- 102650883
- Publisher
- John Wiley and Sons
- Year
- 2000
- Tongue
- English
- Weight
- 863 KB
- Volume
- 45
- Category
- Article
- ISSN
- 0886-1544
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✦ Synopsis
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/␥-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/␥-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/␥-filamin localises in Z-discs already at the first stages of Z-disc formation, suggesting that ABP-L/␥-filamin might play a role in Z-disc assembly.