Required for 27S pre-rRNA processing. Has an early role during 60S ribosomal subunit assembly. Component of very early pre-60S ribosomal particles containing 27SA2 pre-rRNA. Interacts with URB1. Together with DBP6, NOP8, URB1 and RSA3, forms an RNA-independent complex, which is required during early maturation of nascent 60S ribosomal subunits. Present with 1660 molecules/cell in log phase SD medium.