Required for the assembly of mature ribosomes and ribosome biogenesis. Together with K10C3.5b/EFL1, triggers the GTP-dependent release of ribosome maturation factors from 60S pre-ribosomes in the cytoplasm, thereby activating ribosomes for translation competence by allowing 80S ribosome assembly. Required for normal levels of protein synthesis. May play a role in cellular stress resistance. May play a role in cellular response to DNA damage. May play a role in cell proliferation (By similarity). Associates with the 60S ribosomal subunit. Primarily detected in the cytoplasm, and at low levels in nucleus and nucleolus. Detected at the mitotic spindle. Colocalizes with the microtubule organizing center during interphase (By similarity). Belongs to the SDO1/SBDS family.