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mRNP3 and mRNP4 are phosphorylatable by casein kinase II in Xenopus oocytes, but phosphorylation does not modify RNA‐binding affinity
Author(s) -
Deschamps Stéphane,
Jacquemin-Sablon Hélène,
Triqueneaux Gérard,
Mulner-Lorillon Odile,
Potier Michel,
Le Caer Jean-Pierre,
Dautry François,
le Maire Marc
Publication year - 1997
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(97)00833-8
Subject(s) - xenopus , phosphorylation , casein kinase 2 , casein kinase 1 , chemistry , microbiology and biotechnology , protein kinase a , rna , biochemistry , biology , mitogen activated protein kinase kinase , gene
mRNP3 and mRNP4 (also called FRGY2) are two mRNA‐binding proteins which are major constituents of the maternal RNA storage particles of Xenopus laevis oocytes. The phosphorylation of mRNP3–4 has been implicated in the regulation of mRNA masking. In this study, we have investigated their phosphorylation by casein kinase II and its consequence on their affinity for RNA. Comparison of the phosphopeptide map of mRNP3–4 phosphorylated in vivo with that obtained after phosphorylation in vitro by purified Xenopus laevis casein kinase II strongly suggests that casein kinase II is responsible for the in vivo phosphorylation of mRNP3–4 in oocytes. The phosphorylation occurs on a serine residue in a central domain of the proteins. The affinity of mRNP3–4 for RNA substrates remained unchanged after the treatment with casein kinase II or calf intestine phosphatase in vitro. This suggests that phosphorylation of these proteins does not regulate their interaction with RNA but rather controls their interactions with other proteins.