Figure 7. The sso2 mutations have little effect on the actin-independent localization of Sec3.

(A) A control sso1Δ SSO2 strain or sso1Δ sso2 mutants expressing Sec4-GFP were grown to early log phase in YPD at 25°C, then 1 OD₆₀₀ unit cells was collected and resuspended in 50 µl SC medium and incubated with 200 µM Latrunculin A (LatA) or DMSO at 25°C for 15 min prior to imaging. Images were captured by fluorescence microscopy. Sec4 is normally localized near the tip of small buds (arrow) and the neck of large buds (arrowhead) in DMSO-treated cells. Sec4 localization was disrupted in LatA-treated cells. Scale bar, 5 µm (for all images). (B) Quantitation of polarized Sec4-GFP. (C) A control sso1Δ SSO2 strain and the sso1Δ sso2 mutant strains expressing Sec3−3×GFP were grown and treated with LatA or DMSO under the conditions as described in A. Sec3 localization remains polarized after LatA treatment, either at the tips of small bus (arrow) or the necks of large buds (arrow head). Scale bar, 5 µm. (D) Quantitation of polarized Sec3−3×GFP. Error bars represent SDs based on three independent experiments in each case.