de Freitas M S, de Mattos-Dutra A, Schroder N, Wannmacher C M, Pessoa-Pureur R
Departamento de Bioquímica, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Porto Alegre RS, Brazil.
Exp Neurol. 1997 Feb;143(2):188-95. doi: 10.1006/exnr.1996.6351.
We studied the effect of hyperphenylalaninemia on in vitro incorporation of 32P into cytoskeletal proteins from cerebral cortex of rats by injecting l-phenylalanine plus alpha-methylphenylalanine subcutaneously from the 6th to the 14th day postpartum. Chronic hyperphenylalaninemia induced an increased in vitro phosphorylation of the 150-kDa neurofilament subunit and tubulins present in the cytoskeletal fraction at the end of the treatment and 3 days after treatment discontinuation. In addition, when in vitro phosphorylation of the cytoskeletal proteins from treated animals was performed in the presence of the drugs we observed a decreased in vitro incorporation of 32P into these proteins. Thus, the effect of l-phenylalanine plus alpha-methylphenylalanine on the endogenous protein kinase and phosphatase activities was examined and the results demonstrated that these drugs have an inhibitory effect on calcium/calmodulin-dependent protein kinase II and protein phosphatase type 1.
