JBC, Vol. 250, Issue 9, 3560-3566, May, 1975
Purification and characterization of myosin from the clonal rat glial cell strain C-6
J. F. Ash
A myosin was isolated from the clonal rat glial cell strain C-6 and
compared with rat skeletal muscle myosin. After cell extracts were
subjected to gel filtration chromatography in the presence of KI and
magnesium pyrophosphate the C-6 myosin was rapidly purified by a procedure
similar to that used for skeletal muscle myosin. The C-6 myosin resembles
muscle myosin both physically and enzymatically. It contains heavy chains
of 200,000 daltons and two classes of light chains of 17,000 and 19,000
daltons in approximately equal molar ratios. This myosin forms bipolar
thick filaments in 0.1 M KCl and binds reversibly to skeletal muscle
F-actin, the binding being inhibited by MgATP. Skeletal muscle F-actin
stimulates the C-6 myosin adenosine triphosphatase 2- to 3-fold in the
presence of KCl and Mg2+. The action activation of muscle myosin ATPase at
low ionic strength is 10-fold greater than that of C-6 myosin. Ca2+ and
EDTA stimulated the ATPase activities of both enzymes. When assayed in the
presence of 0.6 M KCl and 1 mM EDTA the skeletal muscle myocin ATPase
demonstrates substrate saturation while the C-6 myosin enzyme activity is
stimulated by ATP concentrations above 2.5 mM.
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