Boyer J, Bellé R, Capony JP, Ozon R. Early increase of a 105,000-dalton phosphoprotein during meiotic maturation of Xenopus laevis oocyte.
Biochimie 1983;
65:15-23. [PMID:
6299401 DOI:
10.1016/s0300-9084(83)80024-8]
[Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
In ovo [32P] phosphoproteins were analyzed during meiotic maturation of Xenopus laevis oocytes. A phosphoprotein of 105,000-dalton was found to increase early (one hour) after progesterone induction of meiosis. The pure heat-stable inhibitor (PKI) of cAMP-dependent protein kinase, which induces maturation, was microinjected into oocytes. Again the early increase in the 105,000-dalton [32P] phosphoprotein occurred. The burst in protein phosphorylation, which takes place at the period of germinal vesicle breakdown, was quantitatively and qualitatively comparable in progesterone and PKI-stimulated oocytes. In order to confirm the inverse relationship between the 105,000 dalton [32P] phosphoprotein increase and cAMP-dependent protein kinase activity, purified C-subunit of the kinase has been microinjected into oocytes. C-subunit which inhibits maturation did not increase significantly the 105,000-dalton [32P] phosphoprotein whereas it increased the total level of in ovo phosphorylation. Enucleation experiments favour the localization of the 105,000-dalton protein in both the oocyte cytoplasm and nucleus. Furthermore the progesterone-induced increase in the phosphorylation of the 105,000-dalton protein was found in the cytoplasmic compartment after oocyte enucleation.
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