Characterization of nuclear protein kinases of Xenopus laevis oocytes
Xenopus laevis oocytes contain large nuclei (germinal vesicles) that can be isolated in very pure form and which permit the study of enzymatic activities present in these organelles. Incubation of pure oocyte nuclear homogenates with /sup 32/P in a buffered solution containing 5 mM MgCl/sub 2/ results in the phosphorylation of a large number of proteins by endogenous protein kinases. This phosphorylation is not affected by the addition of cyclic nucleotides or calcium ion and calmodulin. On the other hand the nuclear kinases are considerably stimulated by spermine and spermidine and strongly inhibited by heparin (10 ..mu..g/ml). Addition of exogenous protein substrates shows that the major oocyte kinases are very active with casein and phosvitin as substrates but do not phosphorylate histones or protamines. DEAE-Sephadex chromatography of the nuclear extract fractionates the casein phosphorylating activity in two main peaks. The first peak is not retained on the column equilibrated with 0.1 M NH/sub 2/SO/sub 4/ and uses exclusively ATP as phosphate donor and is insensitive to polyamines or heparin. The second peak which corresponds to 70% of the casein phosphorylation elutes at 0.27 M NH/sub 2/SO/sub 4/ and uses both ATP and GTP as phosphate donors and is greatly stimulated by polyamines and completely inhibited by 10 ..mu..g/ml heparin. On this evidence the authors conclude that the major protein kinase peak corresponds to casein kinase type II which has been found in mammalian nuclei.
- Research Organization:
- Univ. of Chile, Santiago
- OSTI ID:
- 5272576
- Report Number(s):
- CONF-8606151-; TRN: 86-031413
- Journal Information:
- Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Vol. 45:6; Conference: 76. annual meeting of the Federation of American Society for Experimental Biology, Washington, DC, USA, 8 Jun 1986
- Country of Publication:
- United States
- Language:
- English
Similar Records
Protein kinase activity associated with Fc. gamma. /sub 2a/ receptor of a murine macrophage like cell line, P388D/sub 1/
Cyclophilin represents a novel class of protein kinases
Related Subjects
PHOSPHOTRANSFERASES
CHEMICAL COMPOSITION
ENZYME ACTIVITY
PROTEINS
PHOSPHORYLATION
CALCIUM
CELL NUCLEI
CHROMATOGRAPHY
EGGS
FROGS
NUCLEOTIDES
PHOSPHORUS 32
TRACER TECHNIQUES
ALKALINE EARTH METALS
AMPHIBIANS
ANIMALS
AQUATIC ORGANISMS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CELL CONSTITUENTS
CHEMICAL REACTIONS
DAYS LIVING RADIOISOTOPES
ELEMENTS
ENZYMES
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
METALS
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
PHOSPHORUS ISOTOPES
PHOSPHORUS-GROUP TRANSFERASES
RADIOISOTOPES
SEPARATION PROCESSES
TRANSFERASES
VERTEBRATES
550201* - Biochemistry- Tracer Techniques