In the course of the purification of 14-3-3 protein (14-3-3) we found that 14-3-3 isolated from bovine forebrain activates protein kinase C (PKC), rather than the previously reported protein kinase C inhibitory activity (KCIP). We have characterized the 14-3-3 activation of PKC. The physical properties of purified PKC activator are the same as those previously reported for 14-3-3 and KCIP; i.e., (1) it is composed of subunits of molecular weight 32,000, 30,000, and 29,000; (2) it is homogeneous with respect to molecular weight, as judged by native gradient-gel electrophoresis, with a molecular weight of 53,000; and (3) it is composed of at least six isoforms when analyzed by reverse-phase HPLC. The concentration dependence of PKC activation by 14-3-3 is in the same range as that shown previously for KCIP inhibition of PKC, and as that required for 14-3-3 activation of tyrosine hydroxylase; a maximal stimulation of two-to three-fold occurs at 40-100 micrograms/ml. 14-3-3's activation of PKC is sensitive to alpha-chymotrypsin digestion but is not heat labile. Activation is specific to PKC; at least two other protein kinases, cyclic AMP- and calcium/calmodulin-dependent protein kinases, are not activated. The activation of PKC by 14-3-3 is independent of phosphatidylserine and calcium and, as such, is an alternative mechanism for the activation of PKC that obviates its translocation to membranes.
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| rdfs:comment |
In the course of the purification of 14-3-3 protein (14-3-3) we found that 14-3-3 isolated from bovine forebrain activates protein kinase C (PKC), rather than the previously reported protein kinase C inhibitory activity (KCIP). We have characterized the 14-3-3 activation of PKC. The physical properties of purified PKC activator are the same as those previously reported for 14-3-3 and KCIP; i.e., (1) it is composed of subunits of molecular weight 32,000, 30,000, and 29,000; (2) it is homogeneous with respect to molecular weight, as judged by native gradient-gel electrophoresis, with a molecular weight of 53,000; and (3) it is composed of at least six isoforms when analyzed by reverse-phase HPLC. The concentration dependence of PKC activation by 14-3-3 is in the same range as that shown previously for KCIP inhibition of PKC, and as that required for 14-3-3 activation of tyrosine hydroxylase; a maximal stimulation of two-to three-fold occurs at 40-100 micrograms/ml. 14-3-3's activation of PKC is sensitive to alpha-chymotrypsin digestion but is not heat labile. Activation is specific to PKC; at least two other protein kinases, cyclic AMP- and calcium/calmodulin-dependent protein kinases, are not activated. The activation of PKC by 14-3-3 is independent of phosphatidylserine and calcium and, as such, is an alternative mechanism for the activation of PKC that obviates its translocation to membranes.
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| skos:exactMatch | |
| uniprot:name |
J. Neurochem.
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| uniprot:author |
Horwitz R.,
Rosenfeld G.,
Tanji M.,
Waymire J.C.
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| uniprot:date |
1994
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| uniprot:pages |
1908-1916
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| uniprot:title |
Activation of protein kinase C by purified bovine brain 14-3-3: comparison with tyrosine hydroxylase activation.
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| uniprot:volume |
63
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