ed at 532 nm using a Typhoon 9400 scanner. Experimental design, image analysis, and statistics For each transformant, namely Yap1p overexpressing transformant and control transformant, 2 D gels were run in triplicate. Additionally, a master 2 D gel was prepared, which contained a 1,1 mixture of the protein extract from the two yeast transformants. That gel, which should con tain all protein spots present on the 2 D gels with samples from the Yap1p overexpressing and the control transfor mant, was used during image analysis as a master gel. Image analysis was performed using the ImageMaster II software. The quantitative and statistical analyses were performed using suitable functions within the ImageMaster II software and Excel software.

The normalized intensity of spots on three replicate 2 D gels was averaged and the standard de viation was calculated. The relative change in protein abundance for the Yap1p overexpressing transformant versus the control transformant for each protein spot was calculated by div iding the averaged AV-951 spot quantity from gels with samples from the Yap1p overexpressing transformant by the aver aged spot quantity from gels with samples from the con trol transformant. A two tailed non paired Students t test was performed to determine if the relative change was sta tistically significant. In gel tryptic digestion Protein spots of interest were picked from the 2 D gels using an Ettan Spotpicking Station and destained three times using a fresh solution of 20 mM ammonium bicarbonate containing 35% aceto nitrile.

Subsequently, the gel pieces were dried by two washes using 100% neat acetonitrile and re hydrated on ice using a solution of sequencing grade modified trypsin in 20 mM ammonium bicarbonate. The trypsin concentration depended on the intensity of the spots and was 2 to 3 ng ��l. The re hydrated gel samples were incubated in 37 C for over night digestion and either analyzed immediately or stored at ?20 C until further analysis. Mass spectrometry MALDI MS spectra for peptides were acquired using a Voyager DE STR mass spectrometer as described by Yao et al. LC MS MS combined with ESI ion trap MS was performed using an HCT Ultra ETD II mass spectrometer from Bruker linked to an Easy nLC system from Prox eon. Spectra were acquired using the enhanced scanning mode covering a mass range from m z 350 to m z 1300.

The LC separation of peptides was per formed using a 5 um C18 column from NanoSeparations and a 30 min gradient ranging from 0 to 60 percent of acetonitrile. The flow rate was 300 nl min 1. Data proces sing was performed using the Data Analysis software using default setting for processing and AutoMSn detection of compounds. Protein identification Database searches using the peak list files of the processed mass spectra were performed using an in house license of Mascot, and searches were performed using the Swiss Prot or NCBInr database. As for MALDI MS spectra, a mass error of 50 ppm and one missed cleavage sites were