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Glycogen synthase in rat adipocytes and skeletal muscle is phosphorylated on both serine and threonine
Author(s) -
Hiken Jeffrey F.,
Lawrence John C.
Publication year - 1984
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(84)80568-2
Subject(s) - glycogen synthase , phosphorylation , threonine , gsk 3 , chemistry , skeletal muscle , serine , glycogen , glycogen branching enzyme , biochemistry , endocrinology , medicine , microbiology and biotechnology , biology
Glycogen synthase is phosphorylated both in vivo and in vitro on multiple sites per subunit. All phosphorylations of the enzyme thus far identified occur on serines which are found in two cyanogen bromide fragments, denoted CB‐1 and CB‐2. We have immunoprecipitated [ 32 P]glycogen synthase from rat adipocytes and epitrochlearis muscles incubated with [ 32 P]phosphate. Phosphoamino acid analyses by two‐dimensional electrophoresis after acid hydrolysis revealed no [ 32 P]phosphotyrosine, but significant levels of [ 32 P]phosphothreonine (6–14% of the [ 32 P](phosphoserine). The [ 32 P]phosphothreonine was recovered in the large CNBr‐fragment (CB‐2), indicative of a hitherto unknown phosphorylation site(s)