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

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

[No abstract available

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

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

Expression of ribosomal protein genes and regulation of ribosome biosynthesis in Xenopus development

[No abstract available

Ribosomal protein production in normal and anucleolate Xenopus embryos: regulation at the posttranscriptional and translational levels

We have studied the regulation of ribosomal protein (r-protein) synthesis in Xenopus anucleolate mutants, which lack the genes for rRNA. The accumulation of mRNA for the two r-proteins analyzed parallels the controls up to stage 30. This mRNA is mobilized onto polysomes and is translated as in normal embryos, but r-proteins are unstable in the absence of rRNA to assemble with. A translational control of rp-mRNA distribution between polysomes and mRNPs is observed, but this is not due to an autogenous regulation by r-proteins. After stage 30 the amount of rp-mRNA declines specifically in the mutants because the transcripts are unstable. Considering the temporal correlation between this event and the onset of r-protein synthesis we suggest that an autogenous control operates at the level of transcript stability