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Microtubule‐Associated Cyclic AMP‐Dependent Protein Kinase in Drosophila melanogaster
Author(s) -
Ádám Géza,
Friedrich Peter
Publication year - 1988
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.1471-4159.1988.tb03062.x
Subject(s) - protein kinase a , biology , protein subunit , microtubule , mitogen activated protein kinase kinase , map2k7 , cyclin dependent kinase 2 , tubulin , drosophila melanogaster , biochemistry , microbiology and biotechnology , c raf , cyclin dependent kinase complex , kinase , gene
Microtubules were prepared from head extracts of the adult fruit fly, Drosophila melanogaster , by one‐step, taxol‐assisted polymerization. The microtubular fraction displayed cyclic AMP‐dependent protein kinase (protein kinase A) activity, as witnessed by endogenous protein phosphorylation and by protein kinase assay. Microtubule‐bound protein kinase A amounts to 4–5% of total soluble kinase activity, which is almost an order of magnitude less than in mammals. The high‐molecular‐weight microtu‐bule‐associated protein‐2 (MAP‐2), the main binding species for protein kinase A in mammalian brain microtubules, is not detectable in the fly system by protein staining and immunoblotting with anti‐pig MAP‐2 serum, as well as by hybridization of fly DNA with a cDNA probe for human MAP‐2. Cyclic AMP removes a major part of the regulatory (R) subunit of the enzyme from Drosophila microtubules, as demonstrated by enzyme assay, autophosphoryla‐tion of R subunit, and quantitating cyclic AMP binding sites. It is proposed that permanently elevated cyclic AMP levels may elute protein kinase A from crucial intracellular binding sites, thereby interfering with signal transduction.