The economics of ribosome biosynthesis in yeast

In a rapidly growing yeast cell, 60% of total transcription is devoted to r ibosomal RNA, and 50% of RNA polymerase II transcription and 90% of mRNA sp licing are devoted to ribosomal proteins (RPs), Coordinate regulation of th e similar to 150 rRNA genes and 137 RP genes that make such prodigious use of resources is essential for the economy of the cell. This is entrusted to a number of signal transduction pathways that can abruptly induce or silen ce the ribosomal genes, leading to major implications for the expression of other genes as well.