Involved in ribosome biogenesis. Required for processing and efficient intra-nuclear transport of pre-60S ribosomal subunits. Interacts with the AAA-ATPase Midasin, which is essential for the ATP-dependent dissociation of a group of nonribosomal factors from the pre-60S particle. Associates with the pre-60S ribosomal particle. Interacts (via WD repeats) with uL18. Interacts (via UBL domain) with MDN1 (via VWFA/MIDAS domain). Interacts (via WD repeats) with NSA2. Belongs to the NLE1/RSA4 family.