Indications for a novel muscular dystrophy pathway. gamma-filamin, the muscle-specific filamin isoform, interacts with myotilin.

gamma-Filamin, also called ABP-L, is a filamin isoform that is specifically expressed in striated muscles, where it is predominantly localized in myofibrillar Z-discs. A minor fraction of the protein shows subsarcolemmal localization. Although gamma-filamin has the same overall structure as the two other known isoforms, it is the only isoform ...
that carries a unique insertion in its immunoglobulin (Ig)-like domain 20. Sequencing of the genomic region encoding this part of the molecule shows that this insert is encoded by an extra exon. Transient transfections of the insert-bearing domain in skeletal muscle cells and cardiomyocytes show that this single domain is sufficient for targeting to developing and mature Z-discs. The yeast two-hybrid method was used to identify possible binding partners for the insert-bearing Ig-like domain 20 of gamma-filamin. The two Ig-like domains of the recently described alpha-actinin-binding Z-disc protein myotilin were found to interact directly with this filamin domain, indicating that the amino-terminal end of gamma-filamin may be indirectly anchored to alpha-actinin in the Z-disc via myotilin. Since defects in the myotilin gene were recently reported to cause a form of autosomal dominant limb-girdle muscular dystrophy, our findings provide a further contribution to the molecular understanding of this disease.
Mesh Terms:
Adult, Animals, Cell Differentiation, Contractile Proteins, Cytoskeletal Proteins, DNA Transposable Elements, Exons, Humans, Immunoglobulins, Ligands, Mice, Microfilament Proteins, Muscle Proteins, Muscle, Skeletal, Muscular Dystrophies, Myocardium, Myofibrils, Protein Binding, Protein Isoforms, Protein Sorting Signals, Protein Structure, Tertiary, Stem Cells, Two-Hybrid System Techniques
J. Cell Biol.
Date: Oct. 16, 2000
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