The presence of two skeletal muscle alpha-actinins correlates with troponin-tropomyosin expression and Z-line width.
Two species of alpha-actinin from rabbit fast skeletal muscles were identified with a monospecific antisera. Designated alpha-actinin1f and alpha-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. alpha-Actinin1f is expressed with troponin T 1f-alpha beta tropomyosin, and alpha-actinin2f with troponin T 2f-alpha 2 tropomyosin. CNBr peptide maps show that the fast alpha-actinin species differ in primary structure. In contrast, the slow alpha-actinin is indistinguishable from alpha-actinin1f. Further evidence for the similarity of alpha-actinin1f and slow alpha-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 alpha-actinin do not reflect the distinction between fast- and slow-twitch muscles.
D000185:Actinin / Q000145:classification / Q000378:metabolism*; D000818:Animals; D004591:Electrophoresis, Polyacrylamide Gel; D008854:Microscopy, Electron; D009119:Muscle Contraction; D009132:Muscles / Q000502:physiology / Q000648:ultrastructure*; D010446:Peptide Fragments / Q000032:analysis; D011817:Rabbits; D012518:Sarcomeres / Q000648:ultrastructure; D014018:Tissue Distribution; D014335:Tropomyosin / Q000378:metabolism*; D014336:Troponin / Q000378:metabolism*
D010446:Peptide Fragments; D014335:Tropomyosin; D014336:Troponin; D000185:Actinin