Parallel RNA maturation pathways
While ribosome biogenesis constitutes two pre-rRNAs (35S and 5S) and >200 processing factors, the picture for mRNA maturation looks different. S. cerevisiae has ~6000 genes, ~5% of which contain introns, whose transcripts are processed, folded and quality controlled by only ~150 proteins. The question remains whether all of these transcripts are processed by the same proteins along the same maturation pathway. It is known that some genes are transcribed close to the nuclear periphery – is their maturation carried out by a different set of proteins than that of a gene transcribed in the center of the nucleus? Is the same set of proteins processing the mRNA of a housekeeping gene, that maturing a stress-induced mRNA? We are determining whether there exist different maturation pathways, composed of different sets of mRNA maturation factors for different classes of mRNAs in yeast, using proteomic and RNomic approaches. Moreover, we are interested whether, in yeast, the nuclear pores adjacent to the nucleolus, which are devoid of a nuclear basket, are comprising a specialized export route for pre-ribosomes over pre-mRNPs.