Ca2+-mediated phosphorylation and proteolysis activity associated with the cytoskeletal fraction from cerebral cortex of rats |
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Authors: | Marta S. de Freitas Angela de Mattos-Dutra Clóvis M. D. Wannmacher Dr. Regina Pessoa-Pureur |
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Affiliation: | (1) Departamento de Bioquimica, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Rua Sarmento Leite, 500, 90046-900 Porto Alegre, RS, Brasil |
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Abstract: | We describe a Triton-insoluble cytoskeletal fraction extracted from cerebral cortex of young rats retaining an endogenous Ca2+-mediated mechanism acting in vitro on Ca2+/calmodulin-dependent protein kinase II (CaM-KII) activity and on phosphorylation and proteolysis of the 150 kDa neurofilament subunit (NF-M), α and β tubulin. Exogenous Ca2+ induced a 70% decrease in the in vitro phosphorylation of the NF-M and tubulins and a 30–50% decrease in the total amount of these proteins. However, when calpastatin was added basal phosphorylation and NF-M and tubulin content were recovered. Furthermore, exogenous Ca2+/calmodulin induced increased in vitro phosphorylation of the cytoskeletal proteins and CaM-KII activity only in the presence of calpastatin, suggesting the presence of Ca2+-induced calpain-mediated proteolysis. This fraction could be an interesting model to further studies concerning the in vitro effects of Ca2+-mediated protein kinases and proteases associated with the cytoskeletal fraction. |
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Keywords: | Cytoskeletal proteins phosphorylation proteolysis cerebral cortex |
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