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Calcium‐ and Cyclic AMP‐independent, Labile Protein Kinase Appearing during Starfish Oocyte Maturation: its Extraction and Partial Characterization *
Author(s) -
SANO KIYOSHI
Publication year - 1985
Publication title -
development, growth and differentiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.864
H-Index - 66
eISSN - 1440-169X
pISSN - 0012-1592
DOI - 10.1111/j.1440-169x.1985.00263.x
Subject(s) - germinal vesicle , protein kinase a , oocyte , maturation promoting factor , protein kinase c , biology , kinase , microbiology and biotechnology , starfish , protein kinase inhibitor , phosphorylation , cgmp dependent protein kinase , biochemistry , cyclin dependent kinase 2 , chemistry , embryo , cyclin dependent kinase 1 , cell cycle , ecology , cell
A burst of protein phosphorylation and an appearance of maturation‐promoting factor have been reported to occur shortly before germinal vesicle (nucleus) breakdown (GVBD) in 1‐methyladenine‐induced oocyte maturation of starfish. To detect if a protein kinase is activated before GVBD, protein kinase activity was compared in maturing oocytes which were just undergoing GVBD and immature oocytes of Asterina pectinifera. The oocytes were homogenized in a buffer modified from that used for extracting amphibian maturation‐promoting factor. When the supernatant protein of homogenized immature oocytes was used as a substrate, protein kinase activity in the supernatant of the maturing oocytes was 7‐fold higher than that of immature oocytes. The protein kinase in the supernatant of the maturing oocytes showed a high substrate specificity for histone H1 among the exogenous substrates examined, and the activity of the maturing oocytes for histone H1 was 6‐ to 7‐fold higher than that of immature oocytes. The protein kinase detected in the maturing oocytes was very labile and was inhibited neither by ethylene glycol bis(β‐aminoethyl ether)N, N, N′, N′‐tetraacetic acid nor by the heat‐stable inhibitor protein of cyclic AMP‐dependent protein kinase. These results indicate that a calcium‐ and cyclic AMP‐independent, labile “maturation‐specific protein kinase” appeared before GVBD in maturing oocytes, and suggest its participation in the phosphorylation burst in vivo. The possible correlation of this kinase with maturation‐promoting factor and chromosome condensation was discussed.