title: Ribosomal protein production in normal and anucleolate Xenopus embryos: regulation at the posttranscriptional and translational levels.
abstract: 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.
mesh_terms: D000818:Animals; D002466:Cell Nucleolus / Q000502:physiology; D009154:Mutation; D011132:Polyribosomes / Q000378:metabolism; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D012335:RNA, Ribosomal / Q000235:genetics; D012269:Ribosomal Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D014982:Xenopus laevis / Q000196:embryology
chemical_list: D012333:RNA, Messenger; D012335:RNA, Ribosomal; D012269:Ribosomal Proteins