Native cytosolic protein phosphatase‐1 (PP‐1S) containing modulator (inhibitor‐2) is an active enzyme

FEBS Letters

Bollen, Mathieu¹  Stalmans, Willy¹  DePaoli-Roach, Anna A.² 

[1] Afdeling Biochemie, Fakulteit Geneeskunde, Katholieke Universiteit Leuven, B-3000 Leuven, Belgium;Department of Biochemistry and Molecular Biology, Indiana University School of Medecine, Indianapolis, IN 46202-5122, USA

关键词: Protein phosphatase;    Inhibitor-2;    Chaperone;    Skeletal muscle;    GSK-3/FA;    glycogen synthase kinase-3;    also termed protein kinase FA;    PP-1;    protein phosphatase-1;    PP-1S;    soluble (cytosolic) PP-1;    PP-1G;    glycogen-bound protein phosphatase-1;    PP-1C;    catalytic subunit of protein phosphatase-1;   

DOI  :  10.1016/0014-5793(94)00391-2

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

In vitro, the modulator protein (inhibitor-2) slowly converts the catalytic subunit of protein phosphatase-1 (PP-1_c) into an inactive ‘MgATP-dependent form’ that can be reactivated by the transient phosphorylation of modulator with GSK-3/F_A. We report here that this modulator-induced inactivation of PP-1_C can be blocked by addition (at pH 7.5) of either 0.3 mM NaF or 150 mM NaCl, or by raising the pH to 8.5. Making use of a combination of the latter conditions, we have partially purified a soluble modulator-associated form of PP-1 (PP-1S) from rabbit skeletal muscle as a spontaneously active enzyme that cannot be further activated by kinase GSK-3/F_A. These observations argue against a role for the ‘MgATP-dependent’ form of PP-1S as an inactive reservoir of PP-1_C. PP-1S was separated on aminohexyl Sepharose from another active, cytosolic species of PP-1, which appears to be a proteolytic product of the glycogen-bound PP-1G.

【 授权许可】

Unknown