14-3-3 overproduction interferes with late secretory pathway function. (A) Synthetic enhancement of pik1-101 temperature-sensitive growth defect by high copy BMH1/2. The pik1-101 mutant (CSY212) was transformed with 2μ BMH1 (pMB180), 2μ BMH2 (pMB181), 2μ PIK1 (pCS8), or control vector (pRS426), and serial dilutions of cells were tested for growth at 25, 32, or 34°C. (B) Gap1*p-GFP surface transport is similarly impaired in pik1-101 and wild-type cells overexpressing BMH2 (pMB263). Wild-type (NY604) and pik1-101 (YMB064) cells were transformed with Gap1*p-GFP (TPQ99). Cells were grown overnight at 25°C in SCRaf-URA and induced with 3% galactose for 3 h. The temperature shift was performed during the last hour of induction. Cells were analyzed by fluorescence microscopy. Gap1*p-GFP accumulation is indicated by arrowheads. (C) Gap1*p-GFP accumulating structures were counted for pik1-101 (n = 68), wild-type (pRS425; n = 256), wild-type cells overexpressing BMH1 (pMB262; n = 54) or overexpressing BMH2 (pMB263; n = 243). Data are mean ± SEM. (D) Gap1*p-GFP surface activity is reduced in cells overexpressing BMH2. Cells were grown, and Gap1*p-GFP expression was induced as described in B. Gap1*p-GFP activity was determined by measuring the uptake of [14C]citrulline. Data are mean ± SD (n = 3).