Purification and Characterization of Mg2+-Dependent Glycogen Synthase Phosphatase (Phosphoprotein Phosphatase IA) from Rat Liver
Open Access
- 1 October 1981
- journal article
- research article
- Published by Wiley in European Journal of Biochemistry
- Vol. 119 (3) , 503-510
- https://doi.org/10.1111/j.1432-1033.1981.tb05636.x
Abstract
Phosphoprotein phosphatase IA, which represents the major glycogen synthase phosphatase activity in rat liver cytosol, has been purified to apparent homogeneity by chromatography on DEAE-cellulose, histone–Sepharose-4B and Sephadex G-100. The molecular weight of the purified enzyme was 40000 by gel filtration and 48000 by sodium dodecyl sulafte gel electrophoresis, phosphatase IA is therefore a monomeric protein. When treated with 80% ethanol at room temperature, phosphatase IA underwent an inactivation which was totally prevented by 2 mM, MgCl2. Catalytically, phosphatase IA has a preference for glycogen synthase D compared with phosphatases IB and II and obligatorily requires Mg2+or Mn2+for activity. Maximum activity was attained at 5 mM Mgcl2. Since Mg2+does not activate other phosphoprotein phosphatases in rat liver cytosol, we propose the term ‘Mg2+-dependent glycogen synthase phosphatase’ for phosphatase IA.This publication has 37 references indexed in Scilit:
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