The Presence of Two Skeletal Muscle α-Actinins Correlates with Troponin-Tropomyosin Expression and Z-Line Width

• Published in: The Journal of cell biology 1985-09, Vol.101 (3), p.1001-1008
• Main Authors: Schachat, Frederick H., Canine, Amy C., Briggs, Margaret M., Reedy, Mary C.
• Format: Article
• Language: English
• Subjects: Actinin - classification; Actinin - metabolism; Analytical, structural and metabolic biochemistry; Animals; Biological and medical sciences; Contractile proteins; Electrons; Electrophoresis, Polyacrylamide Gel; Fast twitch muscle fibers; Fundamental and applied biological sciences. Psychology; Gels; Holoproteins; Microscopy, Electron; Muscle Contraction; Muscles; Muscles - physiology; Muscles - ultrastructure; Myofibrils; Peptide Fragments - analysis; Proteins; Rabbits; Sarcomeres - ultrastructure; Skeletal muscle; Tissue Distribution; Tongue; Tropomyosin - metabolism; Troponin - metabolism
• ISSN: 0021-9525; 1540-8140
• DOI: 10.1083/jcb.101.3.1001

Two species of α-actinin from rabbit fast skeletal muscles were identified with a monospecific antisera. Designated α -actinin1f and α -actinin2f, their distribution in muscles does not correlate with histochemically defined fast fiber type. Rather, the presence of each correlates with Z-line width and with the expression of different thin filament Ca2+-regulatory complexes. α - actinin1f is expressed with troponin T1f-α β tropomyosin, and α -actinin2f with troponin T2f-α 2 tropomyosin. CNBr peptide maps show that the fast α-actinin species differ in primary structure. In contrast, the slow α-actinin is indistinguishable from α -actinin1f. Further evidence for the similarity of α -actinin1f and slow α-actinin comes from electron microscopic studies which show that fibers that express these species exhibit thick Z-lines. So, unlike other contractile proteins, the multiple forms of α-actinin do not reflect the distinction between fast- and slow-twitch muscles.