Binds to the 60S ribosomal subunit and prevents its association with the 40S ribosomal subunit to form the 80S initiation complex in the cytoplasm. Is also involved in ribosome biogenesis. Associates with pre-60S subunits in the nucleus and is involved in its nuclear export. Cytoplasmic release of TIF6 from 60S subunits and nuclear relocalization is promoted by the GTPase RIA1/EFL1 and by SDO1. Also required for pre-rRNA processing. Monomer. Associates with the 60S ribosomal subunit. Shuttles between cytoplasm and nucleus/nucleolus. Phosphorylation at Ser-174 and Ser-175 promotes nuclear export. Present with 18600 molecules/cell in log phase SD medium. Belongs to the eIF-6 family.