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Multisite phosphorylation of the glycogen‐binding subunit of protein phosphatase‐1 G by cyclic AMP‐dependent protein kinase and glycogen synthase kinase‐3
Author(s) -
Dent Paul,
Campbell David G.,
Hubbard Michael J.,
Cohen Philip
Publication year - 1989
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(89)80433-8
Subject(s) - gsk 3 , glycogen synthase , protein kinase a , phosphorylase kinase , gsk3b , phosphorylation , protein subunit , phosphatase , chemistry , biochemistry , mitogen activated protein kinase kinase , gene
The glycogen‐binding (G) subunit of protein phosphatase‐1 G is phosphorylated stoichiometrically by glycogen synthase kinase‐3 (GSK3), and with a greater catalytic efficiency than glycogen synthase, but only after prior phosphorylation by cyclic AMP‐dependent protein kinase (A‐kinase) at site 1. The residues phosphorylated are the first two serines in the sequence AIFKPGFSPQPSRRGS‐, while the C‐terminal serine (site 1) is one of the two residues phosphorylated by A‐kinase. These findings demonstrate that (i) the G subunit undergoes multisite phosphorylation in vitro; (ii) phosphorylation by GSK3 requires the presence of a C‐terminal phosphoserine residue; (iii) GSK3 can synergise with protein kinases other than casein kinase‐2.