Characterization of beta-actinin: a suppressor of the elongation at the pointed end of thin filaments in skeletal muscle.
We examined the physico-chemical properties and the functions of beta-actinin by using a beta-actinin preparation having the same properties as those reported by Maruyama et al. (J. Biochem. 81, 215-232, 1977). beta-Actinin was composed of two components with molecular weights (estimated by sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis) of 35,000 and 31,000 daltons. Their isoelectric points in 8 M urea were, respectively, 5.9 and 5.4, clearly distinguishable from those of tropomyosin, troponin T and some enzymes having similar molecular weights. beta-Actinin suppressed the polymerization of actin onto the free end, i.e., the pointed end, of thin filaments in an I-Z-I brush prepared by dissolving thick filaments of a myofibril at high ionic strength. Further, beta-actinin suppressed the association of actin to the whole region of an I-Z-I brush. The present study indicates that beta-actinin is composed of two components and functions as a suppressor of elongation at the pointed end of thin filaments, supporting the conclusions of Maruyama et al. (J. Biochem. 81, 215-232, 1977).
D000185:Actinin / Q000302:isolation & purification* / Q000378:metabolism; D000199:Actins / Q000378:metabolism; D000818:Animals; D002458:Cell Fractionation; D004591:Electrophoresis, Polyacrylamide Gel; D046911:Macromolecular Substances; D008970:Molecular Weight; D009132:Muscles / Q000378:metabolism*; D009210:Myofibrils / Q000378:metabolism* / Q000648:ultrastructure; D011485:Protein Binding; D011817:Rabbits
D000199:Actins; D046911:Macromolecular Substances; D000185:Actinin