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Receptor‐Mediated Phosphorylation of Astroglial Intermediate Filament Proteins in Cultured Astroglia
Author(s) -
McCarthy Ken D.,
Prime Judith,
Harmon Teven,
Pollenz Richard
Publication year - 1985
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.1471-4159.1985.tb12875.x
Subject(s) - phosphorylation , glial fibrillary acidic protein , receptor , protein phosphorylation , biology , intermediate filament , vimentin , neurofilament , microbiology and biotechnology , biochemistry , membrane protein , astrocyte , gel electrophoresis , protein kinase a , cell , cytoskeleton , membrane , endocrinology , immunology , central nervous system , immunohistochemistry
Abstract: Primary cultures of purified astroglia have been shown to exhibit a variety of membrane receptors that regulate intracellular cyclic AMP levels. The experiments described in this paper were completed to examine the effect of such receptor agonists on protein phosphorylation in intact astroglia. An analysis of 32 P‐labelled proteins derived from whole cell extracts and separated via two‐dimensional gel electrophoresis indicated that increasing cyclic AMP levels in astroglia stimulated the phosphorylation of two distinct proteins that had apparent molecular weights/isoelectric points (pI) of 51K/ 6.0 and 57K/5.7. Similar experiments with cultured meningeal cells indicated that only the 57K/5.7 protein was phosphorylated in response to elevated levels of cyclic AMP. The 51K/6.0 protein was never observed in gels derived from meningeal cells. Immunoblot experiments indicated that the 51K/6.0 protein stained with antiserum to glial fibrillary acidic protein (GFAP) and the 57K/5.7 protein stained with antibodies to vimentin. Concentration‐effect studies indicate that these proteins are maximally phosphorylated at concentrations of receptor agonists that only slightly elevate cyclic AMP levels. All receptor agonists that have been shown to increase cyclic AMP levels appear similarly efficacious with respect to increasing the phosphorylation of the two proteins. These experiments suggest that the membrane receptors present on astroglia function, in part, to regulate phosphorylation of the intermediate filament proteins GFAP and vimentin.