Study reveals how ribosomes are assembled in human cells

All cells need ribosomes to make the proteins necessary for life. These multi-component molecular machines build complex proteins by stitching building blocks together according to instructions encoded in the cell's messenger RNAs. But ribosomes are themselves composed of small and large subunits, each of which is made up of ribosomal proteins and RNA. Before they can manufacture proteins, these subunits must be manufactured themselves.