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S‐100 Modulates Ca 2+ ‐Independent Phosphorylation of an Endogenous Protein (M r = 19K) in Brain
Author(s) -
Qi DeFang,
Kuo J. F.
Publication year - 1984
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1984.tb06704.x
Subject(s) - phosphorylation , protein kinase a , protamine , endogeny , affinity chromatography , protein phosphorylation , kinase , biochemistry , enzyme , substrate (aquarium) , protein kinase c , calmodulin , chemistry , biology , heparin , ecology
A new brain enzyme (tentatively named protein kinase X), which catalyzes protamine phosphorylation modulated by S‐100, was reported recently. An endogenous substrate protein (M r = 19K) for protein kinase × was isolated from brain by means of S‐100‐Sepharose 4B affinity chromatography. S‐100, but not calmodulin, promoted phosphorylation of the 19K M r protein in a Ca 2+ ‐independent manner, and this reaction was inhibited by gossypol. The substrate protein, localized in the particulate fraction, was present at a much higher level in brain from adult than neonatal rats (2‐day‐old), a developmental change similar to that seen for protein kinase X. It is suggested that a protein phosphorylation system modulated by S‐100 exists in brain, and that this process may be involved in regulation of certain neural functions.