Activation of protein kinase C by purified bovine brain 14-3-3: comparison with tyrosine hydroxylase activation.
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.
Tanji
M
M
Department of Neurobiology and Anatomy, University of Texas Medical School, Houston 77225.
Horwitz
R
R
Rosenfeld
G
G
Waymire
J C
JC
D048948:14-3-3 Proteins; D000818:Animals; D001921:Brain / Q000201:enzymology*; D001923:Brain Chemistry; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation / Q000187:drug effects; D008970:Molecular Weight; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011506:Proteins / Q000032:analysis / Q000302:isolation & purification / Q000494:pharmacology*; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism*
D048948:14-3-3 Proteins; D011506:Proteins; D014446:Tyrosine 3-Monooxygenase; D011493:Protein Kinase C