Heterogeneity in the pre-40S ribosomal subunit reveals two distinct regions of

Ribosomes represent a significant portion of the dry mass of all cells and actively dividing cells assemble about 2,000 ribosomes every minute [1]. This represents a massive investment by the cell in a complex RNA:protein assembly that will go on to translate mRNAs into protein, an essential process for all of life. Much is known about how a ribosome faithfully performs protein synthesis; less is understood about how they are faithfully assembled. Further, several high profile diseases like Diamond Blackfan Anemia (DBA), 5qsyndrome, and isolated congenital asplenia derive from defects in the erythropoetic lineage caused by haploinsufficiency of some ribosomal proteins (r-proteins) [2].