Nuclear Export of the Large Ribosomal Subunit
This extract was created in the absence of an abstract.
Excerpt
The nuclear envelope of eukaryotic cells separates thesite of ribosome synthesis, in the nucleus, from the site offunction, in the cytoplasm. Ribosome biogenesis requiresthe transport of cargo both into and out of the nucleusthrough the nuclear pore complex (NPC). Ribosomal proteins, synthesized in the cytoplasm, are imported into thenucleus where their assembly into ribosomal subunits inthe nucleolus is coordinated with transcription andextensive processing of the ribosomal RNAs (rRNAs)(Kressler et al. 1999; Venema and Tollervey 1999). Theassembled subunits then are exported for translation inthe cytoplasm (Fig. 1). The export of ribosomal subunitsis a major activity in rapidly growing cells. For example,in the budding yeast Saccharomyces cerevisiae, ribosomes are produced and exported at a rate of approximately 2,000 per minute, requiring the nuclear import ofover 150,000 proteins per minute (Warner 1999). Thus,the majority of transport across the nuclear envelope inyeast may well be devoted to ribosome biogenesis...
