Inactivation of protein kinase A is not required for c-mos translation during meiotic maturation of Xenopus oocytes

It has been shown previously that protein kinase A (PKA) maintains Xenopus oocytes arrested at G2, at least in part by preventing c-mos translation, but how PKA controls c-mos translation is not known. Using microinjection of recombinant c-mos, which still activates MAP kinase in the presence of active PKA, we have found that PKA does not exert any effect on translation of endogenous c-mos if MAP kinase is first activated, Even though they accumulate c-mos and contain MAP kinase activity as high as control oocytes, oocytes do not exit G2 in the presence of active PKA, These results are discussed in connection with recent findings on regulation of c-raf activity.