Figure 9 .

Control of Swi6 nucleocytoplasmic shuttling. Swi6 possesses two nuclear localization (NLS) signals, NLS1 and NLS2, which are both regulated by phosphorylation. NLS1 is regulated through the cell cycle, and its function is blocked by phosphorylation on Ser160 by the S-phase CDK, Clb6/Cdc28, resulting in cytoplasmic localization of Swi6 at times other than G1. NLS2 is regulated by cell wall stress and its function is blocked by Mpk1 phosphorylation on Ser238. This feedback inhibitory event down-regulates cell wall stress-induced transcription after activation. Together, these two disparate signals converge to control Swi6 nuclear localization under different conditions. The indicated karyopherins recognize each NLS.