Premium
Does the M‐Phase Promoting Factor (MPF) Activate a Major Ca 2+ ‐and Cyclic Nucleotide‐Independent Protein Kinase in Starfish Ocytes?
Author(s) -
LABBE JEAN CLAUDE,
PICARD ANDRÉ,
DOREE MARCEL
Publication year - 1988
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.1988.00197.x
Subject(s) - maturation promoting factor , protein kinase a , kinase , microinjection , microbiology and biotechnology , phosphatase , biology , cytoplasm , cyclin dependent kinase 2 , protein kinase inhibitor , mitosis , phosphorylation , chemistry , biochemistry , cyclin dependent kinase 1 , cell cycle , cell
In starfish, the activity of a major Ca 2+ ‐and cyclic nuleotide‐independent protein kinase has been shown to fluctuate in phase with that of MPF along meiotic and mitotic cell cycle (23, 25). Microinjection of α‐naphthylphosphate (α‐NP), a potent phosphatase inhibitor, increased considerably (from 15 to 546 picomoles/min/mg protein) the activity of this major cycling kinase in homogenates. Although this result supported the view that kinase phosphorylation might induce its own activation, this hypothesis was eliminated because injection of cytoplasm from hormone‐stimulated enucleated oocytes, which contained the fully activated kinase but no MPF, failed to trigger kinase activation in recipient oocytes. In contrast, kinase activation was induced in recipient oocytes injected with either cytoplasm taken from nucleated maturing oocytes, which contained high MPF and kinase activities, or cytoplasm taken later from hormone‐stimulated and ATP‐γ‐S‐injected oocytes which contained high MPF but low kinase activites. These results indicate that inhibiting dephosphorylation of some regulatory protein activates the M‐phase‐specific protein kinase. The possibility that the M‐phase or maturation‐promoting factor (MPF) might be this regulatory protein is discussed.