Figure 7: Lte1 has a Kin4-independent function in mitotic exit.

(a,b) Targeting of Lte1-GFP to the mother cell cortex via Sfk1-GBP affects SPOC integrity. (a) Representative images showing Lte1-GFP localization in the absence or in the presence of Sfk1-GBP; m, mother, d, daughter cell. Scale bars: 3 μm. (b) Percentage of SPOC-deficient phenotypes observed in the indicated strain backgrounds. Other graphs serve as controls using the strains bearing SFK1-GBP (on the left) and LTE1-GFP (in the middle) separately. Cartoons depict the strain type and protein localization on each set of strains. Each graph is an average of three independent experiments. Error bars are s.d. Per experiment, 100 cells were counted per cell type. (c) K1378E mutation in LTE1-GFP abolishes SPOC deficiency when recruited to the mother cell. Two mutant forms of Lte1-GFP was targeted to the mother cell by Sfk1-GBP. Both K1273E and F1387E are GEF-inactivating mutations at Lte1 C-terminal domain based on homology to Cdc25 (ref. 70). K1273E also impairs Lte1 binding to Ras2 (ref. 70). The table on the right summarizes these properties. Each graph is an average of three independent experiments. Error bars show s.d. Per experiment, 100 cells were counted per cell type. (d) Percentage of SPOC-deficient phenotypes in indicated cell types. ras1/2 corresponds to ras1Δ ras2Δ cells kept alive with overexpression of TPK1. Asterisk indicates significant difference according to two-tailed Student’s t-test (P<0.05). Each bar is an average of three independent experiments. Error bars show s.d. Per experiment, 100 cells were counted per cell type.