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Protein Kinase C in Primary Astrocyte Cultures: Cytoplasmic Localization and Translocation by a Phorbol Ester
Author(s) -
Neary J. T.,
Norenberg L. O. B.,
Norenberg M. D.
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.tb10590.x
Subject(s) - protein kinase c , cytosol , protein kinase a , prkcq , biochemistry , phorbol , phosphorylation , astrocyte , biology , kinase , cgmp dependent protein kinase , cytoplasm , microbiology and biotechnology , mitogen activated protein kinase kinase , enzyme , neuroscience , central nervous system
The distribution of calcium‐activated, phospholipid‐dependent protein kinase (protein kinase C) in supernatant and paniculate fractions of primary cultures of rat astrocytes and its translocation by a phorbol ester were studied. We observed that 91% of protein kinase C activity in astrocytes was in the supernatant fraction, as measured by lysine‐rich histone phosphorylation assay. Attempts to uncover latent activity in the particulate fraction were unsuccessful. Approximately 75% of the supernatant protein kinase C activity could be translocated to the particulate fraction by prior treatment (30–60 min) of the cultures with 100 n M 12‐ O ‐tetradecanoyl‐phorbol 13‐acetate (TPA), but not with 4α‐phorbol, an inactive phorbol ester. Investigation of endogenous substrates for protein kinase C showed that TPA treatment brought about an increase in phosphor ylation in membrane proteins and a decrease in phosphorylation of supernatant proteins. These findings indicate that the distribution of protein kinase C in astrocytes differs substantially from that in whole brain tissue, where approximately two‐thirds of the protein kinase C activity is associated with the particulate fraction. Because protein kinase C is concentrated in the cytosol of astrocytes and most of this activity can be translocated to membranes, astrocytes may be particularly well‐suited to respond to signals that activate phosphoinositide‐linked receptors in brain.