Table 5. Genetic interactions of ppa and ypa mutants with PP2A regulatory subunit mutations.

	par1−Δ	par2−Δ	pab1−Δ
Wild type	Cold sensitive at 19°	No phenotype	Weak cold sensitive
ypa1−Δ	Phenotype of par1−Δ: reduced restrictive temperature	Phenotype of ypa1−Δ: no additive effect	Phenotype of pab1−Δ and cold sensitivity of ypa1−Δ at 19°
ypa2−Δ	Strong negative interaction	Phenotype of ypa2−Δ: no additive effect	Strong negative interaction
ppa1−Δ	par1−Δ phenotype: no negative interaction	Wild-type cells	Phenotype of pab1−Δ: no negative interaction
ppa2−Δ	Phenotype of par1−Δ: strong negative interaction	ppa2−Δ phenotype	Phenotype of pab1−Δ: strong negative interaction

Double mutants of the PP2A regulator subunit null alleles indicated at the top of the table were made with the ppa and ypa mutants indicated. Crosses were analyzed by tetrad dissection and replica plating: spores were initially allowed to form colonies at 32°.