Abstract
Brain actin extracted from an acetone powder of chick brains was purified by a cycle of polymerization-depolymerization followed by molecular sieve chromatography. The brain actin had a subunit molecular weight of 42,000 daltons as determined by co-electrophoresis with muscle actin. It underwent salt-dependent g to f transformation to form double helical actin filaments which could be "decorated" by muscle myosin subfragment 1. A critical concentration for polymerization of 1.3 microM was determined by measuring either the change in viscosity or absorbance at 232 nm. Brain actin was also capable of stimulating the ATPase activity of muscle myosin. Brain myosin was isolated from whole chick brain by a procedure involving high salt extraction, ammonium sulfate fractionation and molecular sieve chromatography. The purified myosin was composed of a 200,000-dalton heavy chain and three lower molecular weight light chains. In 0.6 M KCl the brain myosin had ATPase activity which was inhibited by Mg++, stimulated by Ca++, and maximally activated by EDTA. When dialyzed against 0.1 M KCl, the brain myosin self-assembled into short bipolar filaments. The bipolar filaments associated with each other to form long concatamers, and this association was enhanced by high concentrations of Mg++ ion. The brain myosin did not interact with chicken skeletal muscle myosin to form hybrid filaments. Furthermore, antibody recognition studies demonstrated that myosins from chicken brain, skeletal muscle, and smooth muscle were unique.
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Selected References
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- Ash J. F. Purification and characterization of myosin from the clonal rat glial cell strain C-6. J Biol Chem. 1975 May 10;250(9):3560–3566. [PubMed] [Google Scholar]
- Bray D., Thomas C. Unpolymerized actin in fibroblasts and brain. J Mol Biol. 1976 Aug 25;105(4):527–544. doi: 10.1016/0022-2836(76)90233-3. [DOI] [PubMed] [Google Scholar]
- Chang C. M., Goldman R. D. The localization of actin-like fibers in cultured neuroblastoma cells as revealed by heavy meromyosin binding. J Cell Biol. 1973 Jun;57(3):867–874. doi: 10.1083/jcb.57.3.867. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Eisenberg E., Moos C. The adenosine triphosphatase activity of acto-heavy meromyosin. A kinetic analysis of actin activation. Biochemistry. 1968 Apr;7(4):1486–1489. doi: 10.1021/bi00844a035. [DOI] [PubMed] [Google Scholar]
- Fine R. E., Bray D. Actin in growing nerve cells. Nat New Biol. 1971 Nov 24;234(47):115–118. doi: 10.1038/newbio234115a0. [DOI] [PubMed] [Google Scholar]
- Gordon D. J., Yang Y. Z., Korn E. D. Polymerization of Acanthamoeba actin. Kinetics, thermodynamics, and co-polymerization with muscle actin. J Biol Chem. 1976 Dec 10;251(23):7474–7479. [PubMed] [Google Scholar]
- Higashi S., Oosawa F. Conformational changes associated with polymerization and nucleotide binding in actin molecules. J Mol Biol. 1965 Jul;12(3):843–865. doi: 10.1016/s0022-2836(65)80332-1. [DOI] [PubMed] [Google Scholar]
- KASAI M., ASAKURA S., OOSAWA F. The G-F equilibrium in actin solutions under various conditions. Biochim Biophys Acta. 1962 Feb 12;57:13–21. doi: 10.1016/0006-3002(62)91072-7. [DOI] [PubMed] [Google Scholar]
- Margossian S. S., Lowey S. Substructure of the myosin molecule. IV. Interactions of myosin and its subfragments with adenosine triphosphate and F-actin. J Mol Biol. 1973 Mar 5;74(3):313–330. doi: 10.1016/0022-2836(73)90376-8. [DOI] [PubMed] [Google Scholar]
- Moring S., Ruscha M., Cooke P., Samson F. Isolation and polymerization of brain actin. J Neurobiol. 1975 Mar;6(2):245–255. doi: 10.1002/neu.480060210. [DOI] [PubMed] [Google Scholar]
- Taylor D. L., Rhodes J. A., Hammond S. A. The contractile basis of ameboid movement. II. Structure and contractility of motile extracts and plasmalemma-ectoplasm ghosts. J Cell Biol. 1976 Jul;70(1):123–143. doi: 10.1083/jcb.70.1.123. [DOI] [PMC free article] [PubMed] [Google Scholar]