Characterization of nuclear protein kinases of Xenopus laevis oocytes

Conference · Thu May 01 04:00:00 EDT 1986 · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)

OSTI ID:5272576

Leiva, L; Gonzalez, C; Allende, C; Allende, J

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-
• Conference Information: Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Journal Volume: 45:6
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ALKALINE EARTH METALS
AMPHIBIANS
ANIMALS
AQUATIC ORGANISMS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CALCIUM
CELL CONSTITUENTS
CELL NUCLEI
CHEMICAL COMPOSITION
CHEMICAL REACTIONS
CHROMATOGRAPHY
DAYS LIVING RADIOISOTOPES
EGGS
ELEMENTS
ENZYME ACTIVITY
ENZYMES
FROGS
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
METALS
NUCLEI
NUCLEOTIDES
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
PHOSPHORUS 32
PHOSPHORUS ISOTOPES
PHOSPHORUS-GROUP TRANSFERASES
PHOSPHORYLATION
PHOSPHOTRANSFERASES
PROTEINS
RADIOISOTOPES
SEPARATION PROCESSES
TRACER TECHNIQUES
TRANSFERASES
VERTEBRATES