Abstract
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.
Highlights
A myosln was isolated from the clonal rat glial cell strain C-6 and compared with rat skeletal muscle myosin
When assayed in the presence of 0.6 M KC1 and 1 mu EDTA the skeletal muscle myosln ATPase demonstrates substrate saturation while the C-6 myosin enzyme activity is stimulated by ATP concentrations above 2.5 m&r
This paper describes the purification and some properties of a myosin-like protein isolated from a cell line cloned from a Wistar rat brain tumor [9] and compares this protein with Wistar rat skeletal muscle myosin
Summary
A myosln was isolated from the clonal rat glial cell strain C-6 and compared with rat skeletal muscle myosin. The involvement of actomyosin proteins has been implicated in all these processes (l-8)) and this provides further stimulus for investigations of vertebrate non-muscle cell actin, myosin, and associated proteins. It is important when starting a purification of non-muscle myosin from vertebrate cells to avoid contamination with muscle tissue. This paper describes the purification and some properties of a myosin-like protein isolated from a cell line cloned from a Wistar rat brain tumor [9] and compares this protein with Wistar rat skeletal muscle myosin. The C-6 myosinl is identified by its ability to bind reversibly to actin and show actin-activated adenosine triphosphatase activity; in addition, it shares many other features of muscle myosin
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