Required for 60S ribosomal subunit formation and pre-rRNA processing. Required for normal accumulation of 25S and 5.8S rRNAs. Associates with pre-60S ribosomal particles. Predominantly associated with the 27SA2 pre-rRNA. Can associate with a subset of box H/ACA and box C/D small nucleolar RNPs (snoRNPs) required for peptidyl transferase center modification and with small RNAs snR37 and snR42. Interacts with URB2. Together with DBP6, NOP8, URB2 and RSA3, forms an RNA-independent complex, which is required during early maturation of nascent 60S ribosomal subunits. Accumulates in the immediate vicinity of the dense fibrillar component of the nucleolus. Present with 5890 molecules/cell in log phase SD medium.