FIGURE 2:

The effect of overexpressing individual COPII components on the growth of temperature-sensitive mutants defective in COPII vesicle formation. (A) sec23-1 (MBY8-20C), sec12-4 (MBY10-7A), and sec16-2 (MBY4-1A) cells harboring pEGFP-CFTR were transformed with pYO324 (2 μ vector), pSAR1 (2 μ SAR1), pSEC12 (2 μ SEC12), pSEC23 (2 μ SEC23), pSEC16 (2 μ SEC16), or pSEC13 (2 μ SEC13), and the transformants were grown to saturation at 23ºC in MCD medium lacking uracil and tryptophan (MCD-Ura-Trp). The cells were diluted to a final concentration of 0.3 at OD₆₀₀, and 5 μl of 10-fold dilutions was spotted onto MCD-Ura-Trp plates. The plates were incubated at 23 or 37ºC as indicated. (B) sec23-1 (MBY8-20C) cells transformed with pYO324 (2 μ vector) or pSEC16(2 μ SEC16) were grown at 23 or 37ºC in selective media. Equal amounts of whole-cell extracts were subjected to immunoblotting with anti-CPY antibody. The erv29∆ strain was used as a control. The ER (p1) and mature (m) forms of CPY are indicated.