Figure 6.

A motif in the Ste20 N-terminus affects cell morphology. (A) The indicated fragments were expressed as GST-GFP fusions from the GAL1 promoter (pPP1843, pPP2040, pPP2036, pPP2037, pPP2041, pPP2038, pPP2069, and pPP2070) in wild-type cells (PPY1368). The bud elongation phenotype requires residues 72-120 as well as membrane localization via either the native BR domain or a heterologous membrane-targeting sequence (Cpr vs. control sequence Cpr-SS; Pryciak and Huntress, 1998). (B) Mutations in the morphology-altering domain do not affect the function of full-length Ste20 in mating pathway signaling. PPY913 (ste20Δ) cells harboring the indicated GFP-Ste20 derivatives (pPP316, pPP538, pPP2202, pPP2203, pPP2205, pPP2575, pPP2318, pPP1010, or pPP2356) were tested for induction of FUS1-lacZ by α factor. Results (mean ± SD, n = 4–8) were normalized to wild-type (WT; 100% = 53 β-galactosidase units). “87-91 Ala5” denotes a mutant with Ala replacements at residues 87-91 (SLDDP), which form part of a conserved sequence block (see Supplementary Figure S1).