Extended Data Figure 1. Purification of tagged Nsa1–Nop2 nucleolar pre-60S particles and analysis of RNA components.

a, Schematic of tandem-affinity purification of the nucleolar pre-60S particle with tagged proteins Nsa1 and Nop2. b, Coomassie-blue stained SDS–PAGE of pre-60S particles purified as in a. Protein labels are based on in-solution mass spectrometry analysis of purified pre-60S particles and the approximate molecular weight. c, Schematic processing of the large ribosomal subunit rRNAs in yeast. The locations of the previously published pre-60S particles (the Nog2 particles², the Arx1 particle³⁵, the Rix1–Rea1 particle³ and the Nmd3 particle⁴) are represented by blue bars. Binding sites of northern blot probes are indicated on the 35S and pre-5S transcript. d, e, Pre-rRNA was visualized on an agarose gel and stained using SYBR Green II. Northern blot analysis was performed for the 25S, ITS2, ITS1 and 3′ ETS RNAs (d) and for the 5S rRNA (e).