SAC3 may link nuclear protein export to cell cycle progression

Selective movement of proteins between the nucleus and the cytoplasm is a r egulatory mechanism exploited extensively by the eukaryotic cell. We have i dentified the evolutionarily conserved Sac3 protein, which was implicated p reviously in the regulation of mitosis [Bauer, A. & Kolling. R, (1996) J. c ell Sci. 109, 1575-1583] as a novel mediator of nuclear protein export We s how that Sac3p is localized to the nuclear pore, where it interacts with nu cleoporins, Loss of SAC3 function results in a block in nuclear export of a nuclear export signal-containing reporter protein. Our results also demons trate that SAC3 interacts genetically with the nuclear protein export facto rs Crm1p/Xpo1p and Yrb2p, Taken together, these data indicate a link betwee n nuclear protein export and transition through the cell cycle.