A Nonradioactive Assay to Measure Production and Processing of Ribosomal RNA by 4sU-Tagging

In vivo metabolic pulse labeling is a classical approach to assess production and processing of ribosomal RNA (rRNA). However, conventional labeling techniques can be indirect and require work with radioactivity. Here, we describe in detail a protocol for in vivo metabolic labeling, purification, and readout of nascent rRNA by 4-thiouridine (4sU). We propose 4sU labeling as standard nonradioactive technique for the analysis of rRNA metabolism during ribosome biogenesis.