Translational regulation of the expression of ribosomal protein genes in Xenopus laevis

The mRNAs coding for ribosomal proteins (rp-mRNA) are subjected to translational control during Xenopus oogenesis and embryogenesis, and also during nutritional changes in Xenopus cultured cells. This regulation, which appears to respond to the cellular need for new ribosomes, operates by changing the fraction of rp-mRNA engaged on polysomes, each translated rp-mRNA molecule always remaining fully loaded with ribosomes. All rp-mRNAs analyzed up to now show this translational behavior, and also share some structural features in their untranslated portions. In particular they all have rather short 5' untranslated regions, similar to each other, and always start at the very 5' end with a stretch of several pyrimidines. Fusion to a reporter-coding sequence of the 5' untranslated region of r-protein S19 has shown that this is involved in the translational regulation

Aspects of regulation of ribosomal protein synthesis in Xenopus laevis - Review

The work carried out in the authors' laboratories on the structure and expression of ribosomal protein genes in Xenopus is reviewed, with some comparisons with other systems. These genes form a class that shares several structural features, especially in the region surrounding the 5′ ends. These similar structures appear to be involved in coregulated expression that is attained at various regulatory levels: transcriptional, transcript processing and stability, and translational. Particular attention is paid here to the one operating at the translational level, which has been studied during Xenopus oogenesis and embryogenesis, and also during nutritional changes of Xenopus cultured cells. This regulation, which responds to the cellular need for new ribosomes, operates by changing the fraction of rp-mRNA engaged on polysomes, leaving each translated rp-mRNA molecule always fully loaded with ribosomes. Responsible for this translational behaviour is the typical 5′UTR, which characterizes all rp-mRNAs analyzed up to now, and that can bind in vitro some proteins, putative trans-acting factors for this translational regulation. © 1994 Kluwer Academic Publishers

TOP genes: a translationally controlled class of genes including those coding for ribosomal proteins.

[No abstract available

Translational regulation of the expression of ribosomal protein genes in Xenopus laevis

The mRNAs coding for ribosomal proteins (rp-mRNA) are subjected to translational control during Xenopus oogenesis and embryogenesis, and also during nutritional changes in Xenopus cultured cells. This regulation, which appears to respond to the cellular need for new ribosomes, operates by changing the fraction of rp-mRNA engaged on polysomes, each translated rp-mRNA molecule always remaining fully loaded with ribosomes. All rp-mRNAs analyzed up to now show this translational behavior, and also share some structural features in their untranslated portions. In particular they all have rather short 5' untranslated regions, similar to each other, and always start at the very 5' end with a stretch of several pyrimidines. Fusion to a reporter-coding sequence of the 5' untranslated region of r-protein S19 has shown that this is involved in the translational regulation

Intracellular expression of anti-p21ras single chain Fv fragments inhibits meiotic maturation of xenopus oocytes

The recombinant variable regions of the monoclonal antibody Y13-259, directed against the p21ras protein, have been engineered for expression as intracellular single chain Fv fragments. The activity of the plasmid was confirmed by in vitro and in vivo translation of mRNA showing that the intracellularly expressed single chain fragments are stably and efficiently expressed as cytosolic proteins. The expression of the anti-p21ras single chain antibodies in the cytoplasm of Xenopus laevis oocytes leads to the inhibition of the insulin-induced meiotic maturation. This finding represents the first successful application of the strategy of intracellular antibodies to block a complex biological process in the cytosol of vertebrate cells

Intracellular expression of anti-p21ras single chain Fv fragments inhibits meiotic maturation of xenopus oocytes

The recombinant variable regions of the monoclonal antibody Y13-259, directed against the p21ras protein, have been engineered for expression as intracellular single chain Fv fragments. The activity of the plasmid was confirmed by in vitro and in vivo translation of mRNA showing that the intracellularly expressed single chain fragments are stably and efficiently expressed as cytosolic proteins. The expression of the anti-p21ras single chain antibodies in the cytoplasm of Xenopus laevis oocytes leads to the inhibition of the insulin-induced meiotic maturation. This finding represents the first successful application of the strategy of intracellular antibodies to block a complex biological process in the cytosol of vertebrate cells