Open AccessPhosphorylatlon of a 60 kDa polypeptide fromXenopusoocytes blocks messenger RNA translation
Author(s) -
Denise Kick,
Perry Barrett,
Alison Cummings,
John Sommerville
Publication year - 1987
Publication title -
nucleic acids research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 9.008
H-Index - 537
eISSN - 1362-4954
pISSN - 0305-1048
DOI - 10.1093/nar/15.10.4099
Subject(s) - biology , messenger rna , xenopus , translation (biology) , rna , protein biosynthesis , dephosphorylation , ribonucleoprotein , messenger rnp , microbiology and biotechnology , phosphatase , ribosome , biochemistry , phosphorylation , gene
The stored mRNP particles of Xenopus oocytes contain protein kinase activity and two major phosphoproteins of 60 kDa (pp60) and 56 kDa (pp56). These proteins can be phospholabelled in the particles either in vivo or in vitro and then isolated by SDS-PAGE. On renaturing pp60 in the presence of globin mRNA, a stable RNA-protein complex is formed. The complex has a uniform density in Cs salt gradients, corresponding to the binding of about 10 protein molecules to each mRNA, probably at the poly(A) sequence. Compared with uncomplexed mRNA, the RNP complex is translated poorly both in vitro and in vivo. Translation of the complex can be regained after treatment with protein phosphatase. It is shown that dephosphorylation destabilizes the binding of protein to RNA, making the mRNA accessible for translation. Studies with native mRNP particles show that their translation also can be enhanced by dephosphorylation.