Chick brain actin and myosin. Isolation and characterization

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 sal...

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Bibliographic Details
Published in:The Journal of cell biology 1979-02, Vol.80 (2), p.341-355
Main Authors: Kuczmarski, Edward R., Rosenbaum, Joel L.
Format: Article
Language:English
Subjects:
Actins
Actins - analysis
Actins - isolation & purification
Actins - pharmacology
Adenosine triphosphatases
Adenosine Triphosphatases - metabolism
Animals
Antibodies
Brain
Brain Chemistry
Breast muscle
Chickens
Gels
Gizzard
Molecular Weight
Muscles - enzymology
Myosins - analysis
Myosins - isolation & purification
Neurons
Polymerization
Skeletal muscle
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Summary: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 μM 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.
ISSN:0021-9525
1540-8140
DOI:10.1083/jcb.80.2.341