RESUMO
The levels of cAMP-dependent protein kinase (type I), or cGMP-dependent protein kinase, or protein I, and of a 23,000 MW substrate for the cGMP-dependent protein kinase were measured in cerebella from normal rats and in the cerebella from rats in which a selective loss of interneurons in the cerebellar cortex had been produced by X-irradiation. A decrease was observed in the concentrations of cAMP-dependent protein kinase and of protein I, whereas an increase was observed in the concentrations of cGMP-dependent protein kinase and of the 23,000 MW substrate. The data, taken together with the results of other studies, support the interpretation that cAMP-dependent protein kinase and protein I are distributed throughout the cerebellum, but that cGMP-dependent protein kinase and the 23,000 MW substrate are highly concentrated in Purkinje cells.
Assuntos
Cerebelo/efeitos da radiação , AMP Cíclico/farmacologia , GMP Cíclico/farmacologia , Proteínas do Tecido Nervoso/efeitos da radiação , Proteínas Quinases/metabolismo , Animais , Animais Recém-Nascidos , Cerebelo/enzimologia , Cerebelo/crescimento & desenvolvimento , Cinética , Peso Molecular , Proteínas do Tecido Nervoso/metabolismo , Ratos , Ratos Endogâmicos , Especificidade por SubstratoRESUMO
The regional and cellular distribution of guanosine 3',5'-cyclic monophosphate (cGMP)-dependent protein kinase (ATP:protein phosphotransferase,EC 2.7.1.37) in mammalian brain was examined by use of the photoaffinity label 8-azidoinosine 3',5'-cyclic monophosphate. Of the regions examined, cerebellum had by far the highest concentration of this enzyme. The cellular localization of cGMP-dependent protein kinase within the cerebellum was determined by examination of mutant mice missing specific types of cerebellar neurons. Mutant mice lacking Purkinje cells had greatly reduced amounts of cGMP-dependent protein kinase, whereas the loss of another cell type, granule cells, did not reduce cGMP-dependent protein kinase levels. By using the same strains of mutant mice, a 23,000-dalton soluble cerebellar substrate for cGMP-dependent protein kinase was also shown to be enriched in Purkinje cells. In contrast, the concentration of type I 3',5'-cyclic AMP-dependent protein kinase in the cerebellum was unaffected by the absence of Purkinje cells and only slightly reduced by the absence of granule cells. The enrichment in Purkinje cells of the cGMP-dependent protein kinase and its substrate suggests an important role for cGMP and cGMP-dependent protein phosphorylation in the function of this type of neuronal cell.
