Table 3.

Differential roles of the Ste11p N terminus in the HOG and mating response pathways

	ssk2Δ ssk22Δ ste11Δ				ssk2Δ ssk22Δ ste11Δ ste50Δ
	OsmRa	Mating (%)b	FUS1::LacZc	Arrest (halo)d	OsmRa	Mating (%)b	Fus1::LacZc	Arrest (halo)d
Vector		<1 × 10−4	<0.1			< × 10−4	<0.1
STE11WT	++	11.3	156	Clear		4.3	29	Fill-in
STE11ΔSAM		3.0	30	Fill-in		4.2	36	Fill-in
STE11ΔEE	++	0.1	5		++	<1 × 10−4	ND
STE11ΔSAMEE	+	<1 × 10−4	<0.1		+	<1 × 10−4	ND

^aThe hyperosmolarity-resistant phenotype of yeast cells transformed with different STE11 alleles was scored for growth (+) on selective media with 1.5 M sorbitol for 4 d at 30°C. + indicates hyperosmolarity-resistant phenotype but with noticeably slower growth than wild type (++) on high-osmolarity media. 

^bMating was performed by mixing exponentially growing cells bearing different alleles of STE11 with fivefold excess of DC17 (his1) and incubating for 4 h at 30°C (MATERIALS AND METHODS). Mating efficiency was defined as (the number of diploid cells)/(the number of the experimental haploid cells) × 100. Data represent the mean of two to three independent experiments. 

^cβ-galactosidase activity was determined with yeast cells indicated transformed with different alleles of STE11 and FUS1::LacZ::URA3 plasmid, treated with 1 μM of α-factor for 1.5 h, and the activity was expressed as Miller units (see MATERIALS AND METHODS). Data represent the mean value of two to three independent experiments (the estimate of the error for each value was < 25% of the mean value). 

^dGrowth inhibition was assessed by spotting 5 μg of α-factor on media agar plate embedded with experimental cells bearing different alleles of STE11 and scored after 24 h of incubation at 30°C (see MATERIALS AND METHODS).