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Altered Protein Tyrosine Phosphorylation in Alzheimer's Disease
Author(s) -
Shapiro I. P.,
Masliah E.,
Saitoh T.
Publication year - 1991
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.1471-4159.1991.tb11405.x
Subject(s) - tyrosine , cytosol , phosphorylation , biology , alzheimer's disease , kinase , tyrosine phosphorylation , biochemistry , tyrosine kinase , endocrinology , microbiology and biotechnology , medicine , enzyme , receptor , disease
The activity of protein tyrosine kinases was determined in extracts from Alzheimer's disease brains and age‐and postmortem time‐matched control brains at autopsy using the synthetic peptide substrate poly(Glu 4 Tyr 1 ). The specific activity of protein tyrosine kinases in the particulate fraction decreased roughly twofold ( p < 0.02) in Alzheimer's disease frontal cortex relative to unaffected control cortex. Cytosolic protein tyrosine kinase activity in Alzheimer's disease tissue was not significantly different from that in control tissue. In contrast to reduced particulate protein tyrosine kinase activity, analysis of Western blots of cytosolic and particulate fractions revealed increases in cytosolic antiphosphotyrosine immunoreactive polypeptides with molecular masses of 55 and 60 kDa. Quantitative immunohistochemistry and morphometry of frontal cortex sections with the antiphosphotyrosine antibody indicated increased antiphosphotyrosine staining in the neurons, although the number of antiphosphotyrosine‐positive neurons per square millimeter decreased. Also, increased antiphosphotyrosine staining was observed in the hippocampal neurons. These results suggest that altered protein tyrosine kinases and protein tyrosine phosphorylation are involved in the pathology of Alzheimer's disease.