Figure 3.

Synthetic defects in COPI/arf1Δ double mutants. (A) Growth of strains harboring the arf1Δ allele in combination with sec21–1 (γ-COP), sec21–2 (γ-COP), ret1–1 (α-COP), or sec27–1 (β′-COP) alleles on YPD plates was compared with the corresponding single mutants at the temperatures indicated. Complete genotypes of strains are provided in Table 1. +++, wild-type growth; ++, growth slower than wild type; +, very slow growth (minimal single colony formation); +/−, almost no growth (no single colony formation); and −, complete lethality. (B) COPI mutant strains harboring either the ARF1 wild-type (+) or arf1Δ (Δ) allele were labeled for 10 min and chased for 60 min at the temperature indicated. CPY was recovered by immunoprecipitation and subjected to SDS-PAGE. Positions of the ER (p1) and vacuolar (m) forms of CPY are indicated.