The pore complex-lamina fraction obtained from nuclear envelope contains a protein phosphokinase activity capable of phosphorylating endogenous and exogenous protein substrates. Its specific activity in the presence of MgCl2 is approximately twice that of intact nuclear envelope. However, when MgCl2 is replaced by CoCl2 in the reaction mixture, a 7 to 12-fold increase in incorporation of 32P from γ-32P-ATP into protein substrate occurs. This appears not to be due to an effect of the divalent cation on the substrate, or to inhibition of a phosphoprotein phosphatase activity. Substitution of CuCl2, MnCl2, CaCl2, and ZnCl2 for MgCl2 results in a 20 to 30% decrease in incorporation of 32P. Cyclic AMP and cyclic GMP at 1 μM were without apparent effect. Approximately 40% of the total protein phosphokinase activity of the nuclear envelope is associated with the pore complex-lamina fraction.
|Original language||English (US)|
|Number of pages||7|
|Journal||Biochemical and Biophysical Research Communications|
|State||Published - Feb 12 1980|