Multiple proteins and phosphorylations regulate Saccharomycescerevisiae Cdc24p localization

Targeting of Saccharomyces cerevisiae Cdc24p to polarized growth sites is essential for its function. Localization of GFP-tagged Cdc24 proteins or fragments was assayed in deletion mutants of Cdc24p-interacting proteins. The boi2Δ, ent2Δ, and hua1Δ mutants showed localization defects. The tos2Δ skg6Δ double mutant displayed aberrant pre-anaphase localization to the mother-bud neck region. The same aberrant pattern was seen when potential phosphorylation sites Ser697, Thr704, and Tyr200 were mutated. The S697A mutation also resulted in phosphorylation defects in vivo. These data support roles for Boi2p, Ent2p, Hua1p, Tos2p, and for Cdc24p phosphorylation in targeting Cdc24p to growth sites.