Schizosaccharomyces pombe Mei2p is an RNA-binding protein that switches the cell cycle from mitotic to meiotic. Mei2p forms a unique dot in the nucleus prior to meiosis I, aided by a non-coding RNA molecule termed meiRNA. Here we show that Mei2p intrinsically undergoes nucleocytoplasmic shuttling. Artificial acceleration of nuclear migration of Mei2p advances nuclear dot formation, but meiRNA does not appear to promote the dot formation by modulating the migration rate of Mei2p into the nucleus. Rather, this RNA is likely to facilitate the assembly of Mei2p into a dot structure and trap the protein as such in the nucleus.
