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Proc Natl Acad Sci U S A. April 2, 2002; 99 (7): 4361-6.

Inhibition of Xenopus oocyte meiotic maturation by catalytically inactive protein kinase A.

Schmitt A , Nebreda AR .

Progesterone induces G2-arrested Xenopus oocytes to develop into fertilizable eggs in a process called meiotic maturation. Protein kinase A (PKA), the cAMP-dependent protein kinase, has long been known to be a potent inhibitor of meiotic maturation, but little information is available on how PKA functions. We have cloned two Xenopus PKA catalytic subunit isoforms, XPKAalpha and XPKAbeta. These proteins are 89% identical and both inhibit progesterone-induced meiotic maturation when overexpressed at low levels, suggesting that PKA activity is tightly regulated in the oocyte. Unexpectedly, catalytically inactive XPKA mutants are able to block progesterone-induced maturation as efficiently as the wild-type active XPKA. These mutants also block meiotic maturation induced by Mos, but are less efficient at inhibiting Cdc25C-induced maturation. Our results indicate that PKA can inhibit meiotic maturation by a novel mechanism, which does not require its kinase activity and is also independent of binding to the PKA regulatory subunits.

PubMed ID: 11904361
PMC ID: PMC123653
Article link: Proc Natl Acad Sci U S A.

Genes referenced: cdc25c mos prkacb

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