Nucleolar maturation of the human small subunit processome

Abstract

Making ribosomes in human cells The assembly of the human ribosome requires a vast number of assembly factors that first form a giant precursor of the ribosomal small subunit (SSU), the SSU processome. Singh et al . provide new insights into human ribosome assembly by using cryo–electron microscopy, x-ray crystallography, and functional studies to reveal the structures of the human SSU processome as it matures in the nucleolus. This study reveals the tightly controlled molecular choreography by which an ensemble of assembly factors controls early irreversible maturation steps that bring about the formation of the human SSU. —DJ