Vandermeers A, Vandermeers-Piret MC, Hepburn A, Rathe J, Christophe J. Evidence for the existence of actomyosin ATPase in the rat pancreas. Isolation and biochemical characterization.
EUROPEAN JOURNAL OF BIOCHEMISTRY 1982;
121:295-9. [PMID:
6460617 DOI:
10.1111/j.1432-1033.1982.tb05785.x]
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Abstract
In a crude extract of rat pancreas, myosin was associated with a protein having the same electrophoretic mobility as actin. This myosin was purified after dissociation of the actomyosin complex with KI-ATP. On sodium dodecylsulfate/acrylamide gel electrophoresis, the isolated pancreatic myosin showed a major component of approximately 200 kDa, and two smaller components with apparent molecular weight of 22 and 15 kDa, respectively. This purified myosin exhibited high ATPase activity in the presence of K+ + EDTA or Ca2+ and very little activity in the presence of Mg2+. (K+ + EDTA)-ATPase activity showed one pH optimum at 8.0, while Ca2+-ATPase activity showed two pH optima at 6.0 and 9.0, respectively. (K+ + EDTA)-stimulated enzyme activity was specific for ATP whereas Ca2+-stimulated activity showed low specificity for nucleoside triphosphates.
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