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ACTIVITY OF CYCLIC AMP‐DEPENDENT MICROSOMAL PROTEIN KINASE AND PHOSPHORYLATION OF RIBOSOMAL PROTEIN IN RAT BRAIN DURING POSTNATAL DEVELOPMENT
Author(s) -
Schmidt M. J.,
Sokoloff L.
Publication year - 1973
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.1471-4159.1973.tb07574.x
Subject(s) - protein kinase a , phosphorylation , microsome , biology , ribosomal protein s6 , stimulation , kinase , protein phosphorylation , biochemistry , ribosomal protein , medicine , endocrinology , enzyme , ribosome , rna , gene
— Microsomes from rat brain exhibited protein kinase activity which was stimulated by cyclic AMP when assayed in the presence of exogenous protein substrate, such as thymus histone. In the absence of exogenous substrate some phosphorylation of microsomal protein occurred, but no stimulation by cyclic AMP could be discerned, probably because of limitations of substrate. The maximal activity of microsomal protein kinase observed in the presence of saturating concentrations of histone and the optimal concentration (5 μ m ) of cyclic AMP remained essentially unchanged from birth to early adulthood, but the magnitude of the stimulation by cyclic AMP was significantly higher at birth than at 30 days of age. Brain ribosomal proteins could be phosphorylated by the cyclic AMP‐dependent brain protein kinase. Their total capacity for acceptance of phosphate by means of this phosphorylation reaction remained unchanged throughout the postnatal development of the brain. Our results are consistent with the possibility that phosphorylation of ribosomal protein mediated by cyclic AMP‐dependent protein kinase may play a a role in the postnatal regulation of cerebral protein synthesis, as a result of the changes in the levels of cyclic AMP known to occur in brain during postnatal maturation.