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Synthesis and modification of D7 protein during Xenopus oocyte maturation
Author(s) -
Smith Rosamund C.,
Dworkin Mark B.,
DworkinRastl Eva
Publication year - 1992
Publication title -
molecular reproduction and development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.745
H-Index - 105
eISSN - 1098-2795
pISSN - 1040-452X
DOI - 10.1002/mrd.1080320315
Subject(s) - oocyte , germinal vesicle , xenopus , biology , polysome , messenger rna , microbiology and biotechnology , oogenesis , protein biosynthesis , endogeny , translation (biology) , phosphorylation , translational regulation , rna , biochemistry , ribosome , gene , embryo
Abstract The Xenopus maternal mRNA D7 is translationally repressed during oogenesis, only becoming recruited into polysomes during oocyte maturation, with D7 protein being detectable for the first time prior to germinal vesicle breakdown (GVBD). The synthesis of D7 protein was found to be induced by a variety of maturation‐promoting agents including cyclin, c‐ mos and crude preparations of MPF. D7 protein induced by all these agents is post‐translationally modified and exists as a number of variants of differing molecular weight. In contrast to endogenous D7 mRNA, D7 RNA injected into the stage VI oocyte is efficiently translated, resulting in the accumulation of predominantly unmodified D7 polypeptides, which become increasingly modified during oocyte maturation to produce a pattern of polypeptides similar to those derived from endogenous D7 mRNA. Thus, the system that results in the post‐translational modification of the D7 protein is itself activated during oocyte maturation. The nature of the protein modification is not known but does not appear to be phosphorylation. The translation of exogenous D7 RNA in the stage VI oocyte does not lead to translational derepression of endogenous D7 mRNA.